LTM8003IY

LTM8003 

## 40VIN, 3.5A Step-Down Silent Switcher µModule Regulator 

## **FEATURES** 

## **DESCRIPTION** 

- n **Complete Step-Down Switch Mode Power Supply** n **Low Noise Silent Switcher**[®] **Architecture** 

- n **Wide Input Voltage Range: 3.4V to 40V** 

- n **Wide Output Voltage Range: 0.97V to 18V** 

- n **Wide Temperature Range: –40°C to 150°C (H-Grade)** 

- n **3.5A Continuous Output Current, 6A peak** 

- n **FMEA Compliant Pinout (LTM8003-3.3) Output Stays at or Below Regulation Voltage During Adjacent Pin Short or if a Pin Is Left Floating** 

- n CISPR25 Class 5 Compliant 

- n Selectable Switching Frequency: 200kHz to 3MHz 

- n External Synchronization 

- n Low Quiescent Current: 25µA (5VOUT) 

- n Tiny, Low Profile 6.25mm × 9mm × 3.32mm RoHS Compliant BGA Package 

## **APPLICATIONS** 

- n Automotive Battery Regulation 

The LTM[®] 8003 is a 40VIN, 6A peak, 3.5A continuous step-down Silent Switcher µModule[®] (power module) regulator. The Silent Switcher architecture minimizes EMI while delivering high efficiency at frequencies up to 3MHz. Included in the package are the switching controller, power switches, inductor, and all support components. Operating over an input voltage range of 3.4V to 40V, the LTM8003 supports an output voltage range of 0.97V to 18V and a switching frequency range of 200kHz to 3MHz, each set by a single resistor. Only the input and output filter capacitors are needed to finish the design. 

The low profile package enables utilization of unused space on the bottom of PC boards for high density point of load regulation. The LTM8003 is packaged in a thermally enhanced, compact over-molded ball grid array (BGA) package suitable for automated assembly by standard surface mount equipment. The LTM8003 is RoHS compliant. 

All registered trademarks and trademarks are the property of their respective owners. 

- n Power for Portable Products 

- n Distributed Supply Regulation 

- n Industrial Supplies 

- n Wall Transformer Regulation 

## **TYPICAL APPLICATION** 

**Efficiency, VOUT = 5V** 

## **5VOUT from 7VIN to 40VIN Step-Down Converter** 

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VIN VIN LTM8003<br>7V TO 40V<br>RUN<br>4.7µF VOUT V5VOUT<br>3.5A<br>RT BIAS 6A PEAK<br>41.2k 24.3k 47µF<br>1MHz GND SYNC FB<br>8003 TA01a<br>**----- End of picture text -----**<br>


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PINS NOT USED IN THIS CIRCUIT: TR/SS, PG<br>**----- End of picture text -----**<br>


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95<br>12VIN<br>85<br>75<br>65<br>55<br>0 1 2 3 4<br>LOAD CURRENT (A)<br>8003 TA01<br>EFFICIENCY (%)<br>**----- End of picture text -----**<br>


Rev E 

1 

For more information www.analog.com 

Document Feedback 

## LTM8003 

## **ABSOLUTE MAXIMUM RATINGS** 

## **(Notes 1, 2)** 

VIN, RUN, PG Voltage  .............................................. 42V VOUT, BIAS Voltage  ................................................. 19V FB, TR/SS Voltage ..................................................... 4V SYNC Voltage  ............................................................ 6V 

Maximum Internal Temperature (I-Grade)  ...........  125°C Maximum Internal Temperature (H-Grade)  .........  150°C Storage Temperature (I-Grade)  ...........................  125°C Storage Temperature (H-Grade)  ...........  –50°C to 150°C Peak Reflow Solder Body Temperature  ............... 250°C 

## **PIN CONFIGURATION** 

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TOP VIEW TOP VIEW<br>ADJUSTABLE VERSION FIXED OUTPUT VERSION<br>SYNC TR/SS GND SYNC TR/SS GND<br>A RT A RT<br>GND RUN GND RUN<br>B B<br>PG PG<br>C C<br>BANK2 BANK2<br>VIN VIN<br>D D<br>BANK 1 GND BANK 1 GND<br>E NC E NC<br>FB<br>F F<br>BIAS BIAS<br>G G<br>BANK 3 VOUT BANK 3 VOUT<br>H<br>H<br>1 2 3 4 5 6 1 2 3 4 5 6<br>BGA PACKAGE BGA PACKAGE<br>48-LEAD (9mm × 6.25mm × 3.32mm) BGA PACKAGE 48-LEAD (9mm × 6.25mm × 3.32mm) BGA PACKAGE<br>TJMAX = 150°C, θJA = 24.7°C/W, θJCbottom = 4.5°C/W TJMAX = 150°C, θJA = 24.7°C/W, θJCbottom = 4.5°C/W<br>θJCtop = 22.3°C/W, θJB = 4.2°C/W, WEIGHT = 0.5g θJCtop = 22.3°C/W, θJB = 4.2°C/W, WEIGHT = 0.5g<br>θ VALUES DETERMINED PER JEDEC51-9, 51-12 θ VALUES DETERMINED PER JEDEC51-9, 51-12<br>**----- End of picture text -----**<br>


## **ORDER INFORMATION** 

|**PART NUMBER**|**TERMINAL FINISH**|**PART MARKING***|**PART MARKING***|**PACKAGE**<br>**TYPE**|**MSL**<br>**RATING**|**TEMPERATURE RANGE**|
|---|---|---|---|---|---|---|
|||**DEVICE**|**FINISH CODE**||||
|LTM8003IY#PBF|SAC305(RoHS)|LTM8003|e1|BGA|3|–40°C to 125°C|
|LTM8003HY#PBF|SAC305(RoHS)|LTM8003|e1|BGA|3|–40°C to 150°C|
|LTM8003IY|SnPb(63/37)|LTM8003|e0|BGA|3|–40°C to 125°C|
|LTM8003HY|SnPb(63/37)|LTM8003|e0|BGA|3|–40°C to 150°C|
|LTM8003IY-3.3#PBF|SAC305(RoHS)|LTM8003-3.3|e1|BGA|3|–40°C to 125°C|
|LTM8003HY-3.3#PBF|SAC305(RoHS)|LTM8003-3.3|e1|BGA|3|–40°C to 150°C|



- Device temperature grade is indicated by a label on the shipping container. 

- Pad or ball finish code is per IPC/JEDEC J-STD-609. 

• This product is not recommended for second side reflow. This product is moisture sensitive. For more information, go to Recommended BGA PCB Assembly and Manufacturing Procedures. 

- BGA Package and Tray Drawings 

Rev E 

2 

For more information www.analog.com 

LTM8003 

**ELECTRICAL CHARACTERISTICS The** l **denotes the specifications which apply over the specified operating temperature range, otherwise specifications are at TJ = 25°C. VIN = 12V, RUN = 2V, unless otherwise noted.** 

|**PARAMETER**|**CONDITIONS**|**CONDITIONS**|**MIN**<br>**TYP**<br>**MAX**|**UNITS**|
|---|---|---|---|---|
|Minimum Input Voltage|VINRising|l|3.4|V|
|Output DC Voltage|LTM8003, RFBOpen<br>LTM8003, RFB= 5.62kΩ, VIN= 40V<br>LTM8003-3.3||0.97<br>18<br>3.3|V|
|Peak Output DC Current|VOUT= 3.3V, fSW= 1MHz||6|A|
|Quiescent Current into VIN|RUN = 0V<br>BIAS = 0V, No Load, SYNC = 0V, Not Switching||3<br>8|µA<br>µA|
|Quiescent Current into BIAS|BIAS = 5V, RUN = 0V<br>BIAS = 5V, No Load, SYNC = 0V, Not Switching<br>BIAS = 5V, VOUT= 3.3V, IOUT= 3.5A, fSW= 1MHz||1<br>5<br>12|µA<br>µA<br>mA|
|Line Regulation|5.5V < VIN< 36V, IOUT= 1A||0.5|%|
|Load Regulation|0.1A < IOUT< 3.5A||0.5|%|
|Output Voltage Ripple|IOUT= 3.5A||10|mV|
|Switching Frequency|RT= 232kΩ<br>RT= 41.2kΩ<br>RT= 10.7kΩ||200<br>0.95<br>3|kHz<br>MHz<br>MHz|
|Voltage at FB|LTM8003|l|950<br>970<br>980|mV|
|Minimum BIAS Voltage|(Note 5)||3.2|V|
|RUN Threshold Voltage|||0.9<br>1.06|V|
|RUN Current|||1|µA|
|TR/SS Current|TR/SS = 0V||2|µA|
|TR/SS Pull Down|TR/SS = 0.1V||200|Ω|
|PG Threshold Voltage at FB(Upper)|FB Falling(Note 6, LTM8003)||1.05|V|
|PG Threshold Voltage at FB(Lower)|FB Rising(Note 6, LTM8003)||0.89|V|
|PG Threshold Voltage at VOUT (Upper)|VOUTFalling(Note 6, LTM8003-3.3)||3.57|V|
|PG Threshold Voltage at VOUT (Lower)|VOUTRising(Note 6, LTM8003-3.3)||3.03|V|
|PG Leakage Current|PG = 42V||1|µA|
|PG Sink Current|PG = 0.1V||150|µA|
|SYNC Threshold Voltage|Synchronization||0.4<br>1.5|V|
|SYNC Voltage|To Enable Spread Spectrum||2.9<br>4.2|V|
|SYNC Current|SYNC = 0V||35|µA|



**Note 1:** Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. 

**Note 2:** Unless otherwise noted, the absolute minimum voltage is zero. **Note 3:** The LTM8003I is guaranteed to meet specifications over the full –40°C to 125°C internal operating temperature range. The LTM8003H is guaranteed to meet specifications over the full –40°C to 150°C internal operating temperature range. Note that the maximum internal temperature is determined by specific operating conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors. High junction temperatures degrade operating lifetimes. Operating lifetime is derated at junction temperatures greater than 125°C. 

**Note 4:** The LTM8003 contains overtemperature protection that is intended to protect the device during momentary overload conditions. The internal temperature exceeds the maximum operating junction temperature when the overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. 

**Note 5:** Below this specified voltage, internal circuitry will draw power from VIN. 

**Note 6:** PG transitions from low to high. 

Rev E 

3 

For more information www.analog.com 

LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

## **TA = 25°C, unless otherwise noted.** 

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Efficiency vs Load Current,  Efficiency vs Load Current,  Efficiency vs Load Current,<br>VOUT = 0.97V, BIAS = 5V VOUT = 1.2V, BIAS = 5V VOUT = 1.5V, BIAS = 5V<br>85 90 90<br>75 80 80<br>65 70 70<br>55 12V IN 60 12V IN 60 12V IN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>45 50 50<br>0 1 2 3 4 0 1 2 3 4 0 1 2 3 4<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G01 8003 G02 8003 G03<br>Efficiency vs Load Current,  Efficiency vs Load Current,  Efficiency vs Load Current,<br>VOUT = 1.8V, BIAS = 5V VOUT = 2V, BIAS = 5V VOUT = 2.5V, BIAS = 5V<br>90 90 90<br>80 80 80<br>70 70 70<br>60 12V IN 60 12V IN 60 12V IN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>50 50 55<br>0 1 2 3 4 0 1 2 3 4 0 1 2 3 4<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G04 8003 G05 8003 G06<br>Efficiency vs Load Current,  Efficiency vs Load Current,  Efficiency vs Load Current,<br>VOUT = 3.3V, BIAS = 5V VOUT = 5V, BIAS = 5V VOUT = 8V, BIAS = 5V<br>95 95 95<br>85 85 85<br>75 75 75<br>65 12V IN 65 12V IN 65 12V IN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>55 55 55<br>0 1 2 3 4 0 1 2 3 4 0 1 2 3 4<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G07 8003 G08 8003 G09<br>Rev E<br>EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%)<br>EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%)<br>EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%)<br>**----- End of picture text -----**<br>


4 

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LTM8003 

**TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.** 

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Efficiency vs Load Current,  Efficiency vs Load Current,  Efficiency vs Load Current,<br>VOUT = 12V, BIAS = 5V VOUT = 15V, BIAS = 5V VOUT = 18V, BIAS = 5V<br>95 100 100<br>85 90 90<br>75 80 80<br>65 70 70<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>55 60 60<br>0 1 2 3 4 0 1 2 3 4 0 1 2 3 4<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G10 8003 G11 8003 G12<br>Efficiency vs Load Current,  Efficiency vs Load Current,  Efficiency vs Load Current,<br>VOUT = –3.3V, BIAS Tied to  VOUT = –5V, BIAS Tied to  VOUT = –8V, BIAS Tied to<br>LTM8003 GND LTM8003 GND LTM8003 GND<br>90 90 90<br>80 80 80<br>70 70 70<br>60 5V IN 60 5V IN 60 5V IN<br>12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN<br>50 50 50<br>0 1 2 3 4 0 1 2 3 4 0 1 2 3 4<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G13 8003 G14 8003 G15<br>Efficiency vs Load Current,  Efficiency vs Load Current,  Efficiency vs Load Current,<br>VOUT = –12V, BIAS Tied to  VOUT = –15V, BIAS Tied to  VOUT = –18V, BIAS Tied to<br>LTM8003 GND LTM8003 GND LTM8003 GND<br>90 90 90<br>80 80 80<br>70 70 70<br>60 5V IN 60 12V IN 60 12V IN<br>12VIN 24VIN 24VIN<br>24VIN<br>50 50 50<br>0 1 2 3 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G16 8003 G17 8003 G18<br>Rev E<br>EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%)<br>EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%)<br>EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%)<br>**----- End of picture text -----**<br>


5 

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LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

## **TA = 25°C, unless otherwise noted.** 

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Input vs Load Current  Input vs Load Current  Input vs Load Current<br>VOUT = 0.97V, BIAS = 5V VOUT = 1.2V, BIAS = 5V VOUT = 1.5V, BIAS = 5V<br>0.8 1.00 1.2<br>12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>0.6 0.75 0.9<br>0.4 0.50 0.6<br>0.2 0.25 0.3<br>0 0 0<br>0 2 4 6 0 2 4 6 0 2 4 6<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G19 8003 G20 8003 G21<br>Input vs Load Current  Input vs Load Current  Input vs Load Current<br>VOUT = 1.8V, BIAS = 5V VOUT = 2V, BIAS = 5V VOUT = 2.5V, BIAS = 5V<br>1.25 1.5 1.6<br>12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>1.00 36VIN 1.2 36VIN 36VIN<br>1.2<br>0.75 0.9<br>0.8<br>0.50 0.6<br>0.4<br>0.25 0.3<br>0 0 0<br>0 2 4 6 0 2 4 6 0 2 4 6<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G22 8003 G23 8003 G24<br>Input vs Load Current  Input vs Load Current  Input vs Load Current<br>VOUT = 3.3V, BIAS = 5V VOUT = 5V, BIAS = 5V VOUT = 8V, BIAS = 5V<br>2.5 3.00 5.0<br>12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>2.0 36VIN 36VIN 4.0 36VIN<br>2.25<br>1.5 3.0<br>1.50<br>1.0 2.0<br>0.75<br>0.5 1.0<br>0 0 0<br>0 2 4 6 0 2 4 6 0 2 4 6<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G25 8003 G26 8003 G27<br>Rev E<br>INPUT CURRENT (A) INPUT CURRENT (A) INPUT CURRENT (A)<br>INPUT CURRENT (A) INPUT CURRENT (A) INPUT CURRENT (A)<br>INPUT CURRENT (A) INPUT CURRENT (A) INPUT CURRENT (A)<br>**----- End of picture text -----**<br>


6 

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LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

**TA = 25°C, unless otherwise noted.** 

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Input vs Load Current  Input vs Load Current  Input vs Load Current<br>VOUT = 12V, BIAS = 5V VOUT = 15V, BIAS = 5V VOUT = 18V, BIAS = 5V<br>4 4 5<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>4<br>3 3<br>3<br>2 2<br>2<br>1 1<br>1<br>0 0 0<br>0 2 4 6 0 2 4 6 0.0 1.0 2.0 3.0 4.0 5.0 6<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G28 8003 G29 8003 G30<br>Input vs Load Current  Input vs Load Current  Input vs Load Current<br>VOUT = –3.3V, BIAS Tied to  VOUT = –5V, BIAS Tied to  VOUT = –8V, BIAS Tied to<br>LTM8003 GND LTM8003 GND LTM8003 GND<br>2.5 3 4<br>12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>2.0 36VIN 36VIN<br>3<br>2<br>1.5<br>2<br>1.0<br>1<br>1<br>0.5<br>0 0 0<br>0 2 4 6 0 2 4 6 0 1 2 3 4 5<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G31 8003 G32 8003 G33<br>Input vs Load Current  Input vs Load Current  Input vs Load Current<br>VOUT = –12V, BIAS Tied to  VOUT = –15V, BIAS Tied to  VOUT = –18V, BIAS Tied to<br>LTM8003 GND LTM8003 GND LTM8003 GND<br>4 4 4<br>12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>3 3 3<br>2 2 2<br>1 1 1<br>0 0 0<br>0 1 2 3 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G34 8003 G35 8003 G36<br>Rev E<br>INPUT CURRENT (A) INPUT CURRENT (A) INPUT CURRENT (A)<br>INPUT CURRENT (A) INPUT CURRENT (A) INPUT CURRENT (A)<br>INPUT CURRENT (A) INPUT CURRENT (A) INPUT CURRENT (A)<br>**----- End of picture text -----**<br>


7 

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LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

## **TA = 25°C, unless otherwise noted.** 

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BIAS Current vs Load Current  BIAS Current vs Load Current  BIAS Current vs Load Current<br>VOUT = 0.97V, BIAS = 5V VOUT = 1.2V, BIAS = 5V VOUT = 1.5V, BIAS = 5V<br>4.5 5.0 5.5<br>4.0 5.0<br>4.5<br>3.5 4.5<br>4.0<br>3.0 4.0<br>3.5<br>2.5 12VIN 12VIN 3.5 12VIN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>2.0 3.0 3.0<br>0 2 4 6 0 2 4 6 0 2 4 6<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G37 8003 G38 8003 G39<br>BIAS Current vs Load Current  BIAS Current vs Load Current  BIAS Current vs Load Current<br>VOUT = 1.8V, BIAS = 5V VOUT = 2V, BIAS = 5V VOUT = 2.5V, BIAS = 5V<br>5.5 6.0 6.5<br>5.0 5.5 6.0<br>4.5 5.0 5.5<br>4.0 4.5 5.0<br>3.5 12V IN 4.0 12VIN 4.5 12V IN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>3.0 3.5 4.0<br>0 2 4 6 0 2 4 6 0 2 4 6<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G40 8003 G41 8003 G42<br>BIAS Current vs Load Current  BIAS Current vs Load Current  BIAS Current vs Load Current<br>VOUT = 3.3V, BIAS = 5V VOUT = 5V, BIAS = 5V VOUT = 8V, BIAS = 5V<br>7.0 9 10<br>6.5<br>8 9<br>6.0<br>7 8<br>5.5<br>6 7<br>5.0 12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>4.5 5 6<br>0 2 4 6 0 2 4 6 0 2 4 6<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G43 8003 G44 8003 G45<br>Rev E<br>BIAS CURRENT (mA) BIAS CURRENT (mA) BIAS CURRENT (mA)<br>BIAS CURRENT (mA) BIAS CURRENT (mA) BIAS CURRENT (mA)<br>BIAS CURRENT (mA) BIAS CURRENT (mA) BIAS CURRENT (mA)<br>**----- End of picture text -----**<br>


8 

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LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

**TA = 25°C, unless otherwise noted.** 

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BIAS Current vs Load Current  BIAS Current vs Load Current  BIAS Current vs Load Current<br>VOUT = 12V, BIAS = 5V VOUT = 15V, BIAS = 5V VOUT = 18V, BIAS = 5V<br>12 12 12<br>11<br>11 11<br>10<br>10 10<br>9<br>9 9<br>8<br>8 8<br>7<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>7 6 7<br>0 2 4 6 0 2 4 6 0 2 4 6<br>LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A)<br>8003 G46 8003 G47 8003 G48<br>Dropout Voltage vs Load Current,  Input Current vs VIN Maximum Load Current vs VIN<br>VOUT = 5V, BIAS = 5V VOUT Short Circuited BIAS Open<br>900 2250 6<br>SYNC Grounded<br>SYNC Floating<br>5<br>600 1500 4<br>3<br>300 750 2<br>1 – 3.3VOUT<br>–5VOUT<br>–8VOUT<br>0 0 0<br>0 2 4 6 3 16 28 40 0 10 20 30 40<br>LOAD CURRENT (A) VIN (V) INPUT VOLTAGE (V)<br>8003 G49 8003 G50 8003 G51<br>Maximum Load Current vs VIN Derating, H-Grade, VOUT = 0.97V,  Derating, H-Grade, VOUT = 1.2V,<br>BIAS Open BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board<br>3.5 7 7<br>0 LFM 0 LFM<br>6 6<br>3.0<br>5 5<br>2.5<br>4 4<br>2.0<br>3 3<br>1.5<br>2 2<br>1.0 – 12VOUT 12VIN 12VIN<br>–15VOUT 1 24V IN 1 24V IN<br>–18VOUT 36VIN 36VIN<br>0.5 0 0<br>0 10 20 30 0 25 50 75 100 125 150 0 25 50 75 100 125 150<br>INPUT VOLTAGE (V) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G52 8003 G53 8003 G54<br>Rev E<br>BIAS CURRENT (mA) BIAS CURRENT (mA) BIAS CURRENT (mA)<br>INPUT CURRENT (mA)<br>DROPOUT VOLTAGE (mV)<br>MAXIMUM LOAD CURRENT (A)<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>**----- End of picture text -----**<br>


9 

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LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

## **TA = 25°C, unless otherwise noted.** 

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Derating, H-Grade, VOUT = 1.5V,  Derating, H-Grade, VOUT = 1.8V,  Derating, H-Grade, VOUT = 2V,<br>BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board<br>7 7 7<br>0 LFM 0 LFM 0 LFM<br>6 6 6<br>5 5 5<br>4 4 4<br>3 3 3<br>2 2 2<br>1 12V 24V ININ 1 12V 24V ININ 1 12V 24V ININ<br>36VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 150 0 25 50 75 100 125 150 0 25 50 75 100 125 150<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G55 8003 G56 8003 G57<br>Derating, H-Grade, VOUT = 2.5V,  Derating, H-Grade, VOUT = 3.3V,  Derating, H-Grade, VOUT = 5V,<br>BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board<br>7 7 7<br>0 LFM 0 LFM 0 LFM<br>6 6 6<br>5 5 5<br>4 4 4<br>3 3 3<br>2 2 2<br>1 12V 24V ININ 1 12V 24V ININ 1 12V 24V ININ<br>36VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 150 0 25 50 75 100 125 150 0 25 50 75 100 125 150<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G58 8003 G59 8003 G60<br>Derating, H-Grade, VOUT = 8V,  Derating, H-Grade, VOUT = 12V,  Derating, H-Grade, VOUT = 15V,<br>BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board<br>7 6 6<br>0 LFM 0 LFM 0 LFM<br>6<br>5 5<br>5<br>4 4<br>4<br>3 3<br>3<br>2 2<br>2<br>12VIN 1 1<br>1 24V IN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 150 0 25 50 75 100 125 150 0 25 50 75 100 125 150<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G61 8003 G62 8003 G63<br>Rev E<br>10<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>**----- End of picture text -----**<br>


For more information www.analog.com 

LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

**TA = 25°C, unless otherwise noted.** 

**==> picture [515 x 632] intentionally omitted <==**

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Derating, H-Grade, VOUT = –3.3V,  Derating, H-Grade, VOUT = –5V,<br>Derating, H-Grade, VOUT = 18V,  BIAS Tied to LTM8003 GND,  BIAS Tied to LTM8003 GND,<br>BIAS = 5V, DC2416A Demo Board DC2416A Demo Board DC2416A Demo Board<br>6 6 5<br>0 LFM 0 LFM 0 LFM<br>5 5<br>4<br>4 4<br>3<br>3 3<br>2<br>2 2<br>1 1 12VIN 1 12V IN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 150 0 25 50 75 100 125 150 0 25 50 75 100 125 150<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G64 8003 G65 8003 G66<br>Derating, H-Grade, VOUT = –8V,  Derating, H-Grade, VOUT = –12V,  Derating, H-Grade, VOUT = –15V,<br>BIAS Tied to LTM8003 GND,  BIAS Tied to LTM8003 GND,  BIAS Tied to LTM8003 GND,<br>DC2416A Demo Board DC2416A Demo Board DC2416A Demo Board<br>4 4 2.5<br>0 LFM 0 LFM 0 LFM<br>2.0<br>3 3<br>1.5<br>2 2<br>1.0<br>1 1<br>0.5<br>12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>0 0 0<br>0 25 50 75 100 125 150 0 25 50 75 100 125 150 0 25 50 75 100 125 150<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G67 8003 G68 8003 G69<br>Derating, H-Grade, VOUT = –18V,<br>BIAS Tied to LTM8003 GND,  Derating, I-Grade, VOUT = 0.97V,  Derating, I-Grade, VOUT = 1.2V,<br>DC2416A Demo Board BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board<br>2.0 7 7<br>0 LFM 0 LFM 0 LFM<br>6 6<br>1.5<br>5 5<br>4 4<br>1.0<br>3 3<br>2 2<br>0.5<br>1 12V 24V ININ 1 12V 24V ININ<br>12VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 150 0 25 50 75 100 125 0 25 50 75 100 125<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G70 8003 G71 8003 G72<br>Rev E<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>**----- End of picture text -----**<br>


11 

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LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

## **TA = 25°C, unless otherwise noted.** 

**==> picture [512 x 621] intentionally omitted <==**

**----- Start of picture text -----**<br>
Derating, I-Grade, VOUT = 1.5V,  Derating, I-Grade, VOUT = 1.8V,  Derating, I-Grade, VOUT = 2V,<br>BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board<br>7 7 7<br>0 LFM 0 LFM 0 LFM<br>6 6 6<br>5 5 5<br>4 4 4<br>3 3 3<br>2 2 2<br>1 12V 24V ININ 1 12V 24V ININ 1 12V 24V ININ<br>36VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 0 25 50 75 100 125 0 25 50 75 100 125<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G73 8003 G74 8003 G75<br>Derating, I-Grade, VOUT = 2.5V,  Derating, I-Grade, VOUT = 3.3V,  Derating, I-Grade, VOUT = 5V,<br>BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board<br>7 7 6<br>0 LFM 0 LFM 0 LFM<br>6 6<br>5<br>5 5<br>4<br>4 4<br>3<br>3 3<br>2<br>2 2<br>12VIN 12VIN 1 12VIN<br>1 24V IN 1 24V IN 24VIN<br>36VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 0 25 50 75 100 125 0 25 50 75 100 125<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G76 8003 G77 8003 G78<br>Derating, I-Grade, VOUT = 8V,  Derating, I-Grade, VOUT = 12V,  Derating, I-Grade, VOUT = 15V,<br>BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board BIAS = 5V, DC2416A Demo Board<br>6 6 6<br>0 LFM 0 LFM 0 LFM<br>5 5 5<br>4 4 4<br>3 3 3<br>2 2 2<br>1 12VIN 1 1<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 0 25 50 75 100 125 0 25 50 75 100 125<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G79 8003 G80 8003 G81<br>Rev E<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>**----- End of picture text -----**<br>


12 

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LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

**TA = 25°C, unless otherwise noted.** 

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Derating, I-Grade, VOUT = –3.3V,  Derating, I-Grade, VOUT = –5V,<br>Derating, I-Grade, VOUT = 18V,  BIAS Tied to LTM8003 GND,  BIAS Tied to LTM8003 GND,<br>BIAS = 5V, DC2416A Demo Board DC2416A Demo Board DC2416A Demo Board<br>6 6 5<br>0 LFM 0 LFM 0 LFM<br>5 5<br>4<br>4 4<br>3<br>3 3<br>2<br>2 2<br>1 1 12VIN 1 12V IN<br>24VIN 24VIN 24VIN<br>36VIN 36VIN 36VIN<br>0 0 0<br>0 25 50 75 100 125 0 25 50 75 100 125 0 25 50 75 100 125<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G82 8003 G83 8003 G84<br>Derating, I-Grade, VOUT = –8V,  Derating, I-Grade, VOUT = –12V,  Derating, I-Grade, VOUT = –15V,<br>BIAS Tied to LTM8003 GND,  BIAS Tied to LTM8003 GND,  BIAS Tied to LTM8003 GND,<br>DC2416A Demo Board DC2416A Demo Board DC2416A Demo Board<br>5 3 2.0<br>0 LFM 0 LFM 0 LFM<br>4<br>1.5<br>2<br>3<br>1.0<br>2<br>1<br>0.5<br>1<br>12VIN 12VIN 12VIN<br>24VIN 24VIN 24VIN<br>0 0 0<br>0 25 50 75 100 125 0 25 50 75 100 125 0 25 50 75 100 125<br>AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C)<br>8003 G85 8003 G86 8003 G87<br>Derating, I-Grade, VOUT = –18V,  CISPR25 Class 5 Peak Radiated  CISPR25 Class 5 Average Radiated<br>BIAS Tied to LTM8003 GND,  DC2416A Demo Board, VOUT = 5V  DC2416A Demo Board, VOUT = 5V<br>DC2416A Demo Board Spread Spectrum Enabled Spread Spectrum Enabled<br>2.0 50 50<br>0 LFM VERTICAL POLARIZATION<br>fSW = 2MHz<br>40 40 I OUT  = 3.5A<br>1.5<br>30 30<br>1.0 20 20<br>10 10<br>0.5<br>0 VERTICAL POLARIZATION 0<br>fSW = 2MHz<br>12VIN IOUT = 3.5A<br>0 –10 –10<br>0 25 50 75 100 125 0 10 20 30 0 10 20 30<br>AMBIENT TEMPERATURE (°C) FREQUENCY (MHz) FREQUENCY (MHz)<br>8003 G88 8053 G89 8053 G90<br>Rev E<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A) MAXIMUM LOAD CURRENT (A)<br>AMPLITUDE (dBuV/m) AMPLITUDE (dBuV/m)<br>MAXIMUM LOAD CURRENT (A)<br>**----- End of picture text -----**<br>


13 

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## LTM8003 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

**TA = 25°C, unless otherwise noted.** 

**CISPR25 Class 5 Peak Radiated DC2416A Demo Board, VOUT = 5V Spread Spectrum Enabled** 

**CISPR25 Class 5 Average Radiated DC2416A Demo Board, VOUT = 5V Spread Spectrum Enabled** 

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50<br>40<br>30<br>20<br>10<br>0<br>fSW = 2MHz<br>IOUT = 3.5A<br>–10<br>0 200 400 600 800 1000<br>FREQUENCY (MHz)<br>8053 G91<br>AMPLITUDE (dBuV/m)<br>**----- End of picture text -----**<br>


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50<br>VERTICAL POLARIZATION<br>fSW = 2MHz<br>40 I OUT  = 3.5A<br>30<br>20<br>10<br>0<br>–10<br>0 200 400 600 800 1000<br>FREQUENCY (MHz)<br>8053 G92<br>AMPLITUDE (dBuV/m)<br>**----- End of picture text -----**<br>


## **PIN FUNCTIONS** 

**GND (Bank 1, A1, A6):** Tie these GND pins to a local ground plane below the LTM8003 and the circuit components. In most applications, the bulk of the heat flow out of the LTM8003 is through these pads, so the printed circuit design has a large impact on the thermal performance of the part. See the PCB Layout and Thermal Considerations sections for more details. 

**VIN (Bank 2):** VIN supplies current to the LTM8003’s internal regulator and to the internal power switch. These pins must be locally bypassed with an external, low ESR capacitor; see Table 1 for recommended values. 

**VOUT (Bank 3):** Power Output Pins. Apply the output filter capacitor and the output load between these pins and GND pins. 

**BIAS (Pins G1, G2):** The BIAS pin connects to the internal power bus. Connect to a power source greater than 3.2V and less than 18V. If VOUT is greater than 3.2V, connect this pin there. If the output voltage is less, connect this to a voltage source above 3.2V. Decouple this pin with at least 1µF if the voltage source for BIAS is remote. If unused or generating a negative output, tie BIAS to LTM8003 GND. 

**RUN (Pins B5, B6):** Pull the RUN pin below 0.9V to shut down the LTM8003. Tie to 1.06V or more for normal operation. If the shutdown feature is not used, tie this pin to the VIN pin. 

**RT (Pins A4, A5):** The RT pin is used to program the switching frequency of the LTM8003 by connecting a resistor from this pin to ground. The Applications Information section of the data sheet includes a table to determine the resistance value based on the desired switching frequency. Minimize capacitance at this pin. Do not drive this pin. 

**SYNC (Pins A2, B2):** External clock synchronization input and operational mode. This pin programs four different operating modes: 

1. Burst Mode[®] . Tie this pin to ground for Burst Mode operation at low output loads—this will result in ultralow quiescent current. 

2. Pulse-skipping mode. Float this pin for pulse-skipping mode. This mode offers full frequency operation down to low output loads before pulse skipping occurs. 

3. Spread spectrum mode. Tie this pin high (between 2.9V and 4.2V) for pulse-skipping mode with spread spectrum modulation. 

4. Synchronization mode. Drive this pin with a clock source to synchronize to an external frequency. During synchronization the part will operate in pulse-skipping mode. 

**PG (Pin B1, C1):** The PG pin is the open-collector output of an internal comparator. PG remains low until the FB pin voltage is within about 10% of the final regulation 

Rev E 

14 

For more information www.analog.com 

LTM8003 

## **PIN FUNCTIONS** 

voltage. The PG signal is valid when VIN is above 3.4V. If VIN is above 3.4V and RUN is low, PG will drive low. If this function is not used, leave this pin floating. 

**FB (Pin F1, F2):** The LTM8003 regulates its FB pin to 0.97V. Connect the adjust resistor from this pin to ground. The value of RFB is given by the equation RFB = 97/(VOUT – 0.97), where RFB is in kΩ. 

**TR/SS (Pin A3, B3):** The TR/SS pin is used to provide a soft-start or tracking function. The internal 2μA pull-up 

current in combination with an external capacitor tied to this pin creates a voltage ramp. If TR/SS is less than 0.97V, the output voltage tracks to this value. For tracking, tie a resistor divider to this pin from the tracked output. This pin is pulled to ground with an internal MOSFET during shutdown and fault conditions; use a series resistor if driving from a low impedance output. This pin may be left floating if the tracking function is not needed. 

**NC (Pins C5, D5, E5, E6):** These pins are not connected, either to any other net or each other. 

## **BLOCK DIAGRAM** 

**LTM8003 Block Diagram** 

**==> picture [271 x 405] intentionally omitted <==**

**----- Start of picture text -----**<br>
VIN<br>BIAS<br>CURRENT 1.3µH VOUT<br>0.2µF MODE<br>CONTROLLER<br>100k 10pF<br>0.01µF<br>GND<br>FB<br>RUN<br>TR/SS SYNC RT PG<br>8003 BD01<br>LTM8003-3.3 Block Diagram<br>VIN<br>BIAS<br>CURRENT 1.3µH VOUT<br>0.2µF MODE<br>CONTROLLER<br>10pF<br>INTERNAL<br>0.01µF<br>0.97V<br>RUN FEEDBACK<br>GND<br>TR/SS SYNC RT PG<br>8003 BD02<br>**----- End of picture text -----**<br>


Rev E 

15 

For more information www.analog.com 

LTM8003 

## **OPERATION** 

The LTM8003 is a stand-alone non-isolated step-down switching DC/DC power supply that can deliver up to 6A. The continuous current is determined by the internal operating temperature. It provides a precisely regulated output voltage programmable via one external resistor from 0.97V to 18V. The input voltage range is 3.4V to 40V. Given that the LTM8003 is a step-down converter, make sure that the input voltage is high enough to support the desired output voltage and load current. Simplified Block Diagrams are given on the previous page. 

The LTM8003 contains a current mode controller, power switching elements, power inductor and a modest amount of input and output capacitance. The LTM8003 is a fixed frequency PWM regulator. The switching frequency is set by simply connecting the appropriate resistor value from the RT pin to GND. 

An internal regulator provides power to the control circuitry. This bias regulator normally draws power from the VIN pin, but if the BIAS pin is connected to an external voltage higher than 3.2V, bias power is drawn from the external source (typically the regulated output voltage). This improves efficiency. The RUN pin is used to place the LTM8003 in shutdown, disconnecting the output and reducing the input current to a few µA. 

To enhance efficiency, the LTM8003 automatically switches to Burst Mode operation in light or no load situations. Between bursts, all circuitry associated with controlling the output switch is shut down reducing the input supply current to just a few µA. 

The oscillator reduces the LTM8003’s operating frequency when the voltage at the FB pin is low. This frequency foldback helps to control the output current during start-up and overload. 

The TR/SS node acts as an auxiliary input to the error amplifier. The voltage at FB servos to the TR/SS voltage until TR/SS goes above about 0.97V. Soft-start is implemented by generating a voltage ramp at the TR/SS pin using an external capacitor which is charged by an internal constant current. Alternatively, driving the TR/SS pin with a signal source or resistive network provides a tracking function. Do not drive the TR/SS pin with a low impedance voltage source. See the Applications Information section for more details. 

The LTM8003 contains a power good comparator which trips when the FB pin is at about 90% to 110% of its regulated value. The PG output is an open-drain transistor that is off when the output is in regulation, allowing an external resistor to pull the PG pin high. The PG signal is valid when VIN is above 3.4V. If VIN is above 3.4V and RUN is low, PG will drive low. 

The LTM8003 is equipped with a thermal shutdown that inhibits power switching at high junction temperatures. The activation threshold of this function is above the maximum temperature rating to avoid interfering with normal operation, so prolonged or repetitive operation under a condition in which the thermal shutdown activates may damage or impair the reliability of the device. 

Rev E 

16 

For more information www.analog.com 

LTM8003 

## **APPLICATIONS INFORMATION** 

For most applications, the design process is straightforward, summarized as follows: 

1. Look at Table 1 and find the row that has the desired input range and output voltage. 

2. Apply the recommended CFF, CIN, COUT, RFB and RT values. 

3. Apply the CFF (from VOUT to FB) as required. 

4. Connect BIAS as indicated. 

While these component combinations have been tested for proper operation, it is incumbent upon the user to verify proper operation over the intended system’s line, 

load and environmental conditions. Bear in mind that the maximum output current is limited by junction temperature, the relationship between the input and output voltage magnitude and polarity and other factors. Please refer to the graphs in the Typical Performance Characteristics section for guidance. 

The maximum frequency (and attendant RT value) at which the LTM8003 should be allowed to switch is given in Table 1 in the Maximum fSW column, while the recommended frequency (and RT value) for optimal efficiency over the given input condition is given in the fSW column. There are additional conditions that must be satisfied if the synchronization function is used. Please refer to the Synchronization section for details. 

**Table 1. Recommended Component Values and Configuration (TA = 25°C)** 

|**VIN**|**VOUT**<br>**(V)**|**RFB**<br>**(kΩ)**|**CIN2**|**COUT**|**CFF**<br>**(pF)**|**BIAS**<br>**(V)**|**fSW**|**RT**<br>**(kΩ)**|**Maximum**<br>**fSW**|**Minimum RT**<br>**(kΩ)**|
|---|---|---|---|---|---|---|---|---|---|---|
|3.4V to 40V|0.97|Open|4.7µF 50V 1206 X5R|2x 100µF 6.3V 1210 X5R|47|3.2 to 19|450kHz|97.6|675kHz|63.4|
|3.4V to 40V|1.2|402|4.7µF 50V 1206 X5R|2x 100µF 6.3V 1210 X5R|47|3.2 to 19|550kHz|78.7|850kHz|49.9|
|3.4V to 40V|1.5|174|4.7µF 50V 1206 X5R|100µF 6.3V 1210 X5R|27|3.2 to 19|600kHz|71.5|1.1MHz|36.5|
|3.4V to 40V|1.8|115|4.7µF 50V 1206 X5R|100µF 6.3V 1210 X5R|10|3.2 to 19|600kHz|71.5|1.3MHz|30.9|
|3.4V to 40V|2.0|90.9|4.7µF 50V 1206 X5R|100µF 0805 4V X5R||3.2 to 19|650kHz|64.9|1.4MHz|28.0|
|4V to 40V1|2.5|63.4|4.7µF 50V 1206 X5R|100µF 0805 4V X5R||3.2 to 19|750kHz|56.2|1.8MHz|20.5|
|5V to 40V1|3.3|41.2|4.7µF 50V 1206 X5R|100µF 0805 4V X5R||3.2 to 19|850kHz|48.7|2.3MHz|14.7|
|7V to 40V1|5|24.3|4.7µF 50V 1206 X5R|47µF 6.3V 0805 X5R||3.2 to 19|1MHz|40.2|3MHz|10.7|
|11V to 40V1|8|13.7|4.7µF 50V 1206 X5R|22µF 1206 10V X7R||3.2 to 19|1.2MHz|33.2|3MHz|10.7|
|16V to 40V1|12|8.66|4.7µF 50V 1206 X5R|10µF 0805 16V X7S||3.2 to 19|1.5MHz|25.5|3MHz|10.7|
|19.5 to 40V1|15|6.81|4.7µF 50V 1206 X5R|10µF 0805 16V X7S||3.2 to 19|1.5MHz|25.5|3MHz|10.7|
|23.5V to 40V1|18|5.62|4.7µF 50V 1206 X5R|10µF 1206 25V X5R||3.2 to 19|1.5MHz|25.5|3MHz|10.7|
|5V to 22V1|–18|5.62|4.7µF 50V 1206 X5R|10µF 1206 25V X5R||LTM8003 GND|1.5MHz|25.5|3MHz|10.7|
|4.5V to 25V1|–15|6.81|4.7µF 50V 1206 X5R|10µF 0805 16V X7S||LTM8003 GND|1.5MHz|25.5|3MHz|10.7|
|3.4V to 28V1|–12|8.66|4.7µF 50V 1206 X5R|10µF 0805 16V X7S||LTM8003 GND|1.5MHz|25.5|3MHz|10.7|
|3.4V to 32V1|–8|13.7|4.7µF 50V 1206 X5R|22µF 1206 10V X7R||LTM8003 GND|1.2MHz|33.2|3MHz|10.7|
|3.4V to 351|–5|24.3|4.7µF 50V 1206 X5R|47µF 6.3V 0805 X5R||LTM8003 GND|1MHz|40.2|3MHz|10.7|
|3.4V to 36V1|–3.3|41.2|4.7µF 50V 1206 X5R|100µF 0805 4V X5R||LTM8003 GND|850kHz|48.7|2.3MHz|14.7|



1. The LTM8003 may be capable of lower input voltages but may skip switching cycles. 

2. An input bulk capacitor is required 

Rev E 

17 

For more information www.analog.com 

LTM8003 

## **APPLICATIONS INFORMATION** 

## **Capacitor Selection Considerations** 

The CIN and COUT capacitor values in Table 1 are the minimum recommended values for the associated operating conditions. Applying capacitor values below those indicated in Table 1 is not recommended and may result in undesirable operation. Using larger values is generally acceptable, and can yield improved dynamic response, if it is necessary. Again, it is incumbent upon the user to verify proper operation over the intended system’s line, load and environmental conditions. 

Ceramic capacitors are small, robust and have very low ESR. However, not all ceramic capacitors are suitable. X5R and X7R types are stable over temperature and applied voltage and give dependable service. Other types, including Y5V and Z5U have very large temperature and voltage coefficients of capacitance. In an application circuit they may have only a small fraction of their nominal capacitance resulting in much higher output voltage ripple than expected. 

Ceramic capacitors are also piezoelectric. In Burst Mode operation, the LTM8003’s switching frequency depends on the load current, and can excite a ceramic capacitor at audio frequencies, generating audible noise. Since the LTM8003 operates at a lower current limit during Burst Mode operation, the noise is typically very quiet to a casual ear. 

If this audible noise is unacceptable, use a high performance electrolytic capacitor at the output. It may also be a parallel combination of a ceramic capacitor and a low cost electrolytic capacitor. 

A final precaution regarding ceramic capacitors concerns the maximum input voltage rating of the LTM8003. A ceramic input capacitor combined with trace or cable inductance forms a high-Q (underdamped) tank circuit. If the LTM8003 circuit is plugged into a live supply, the input voltage can ring to twice its nominal value, possibly exceeding the device’s rating. This situation is easily avoided; see the Hot-Plugging Safely section. 

## **Frequency Selection** 

The LTM8003 uses a constant frequency PWM architecture that can be programmed to switch from 200kHz to 3MHz by using a resistor tied from the RT pin to ground. Table 2 provides a list of RT resistor values and their resultant frequencies. 

**Table 2. SW Frequency vs RT Value** 

|**fSW (MHz)**|**RT (kΩ)**|
|---|---|
|0.2|232|
|0.3|150|
|0.4|110|
|0.5|88.7|
|0.6|71.5|
|0.7|60.4|
|0.8|52.3|
|1.0|40.2|
|1.2|33.2|
|1.4|28.0|
|1.6|23.7|
|1.8|20.5|
|2.0|18.2|
|2.2|15.8|
|3.0|10.7|



## **Operating Frequency Trade-Offs** 

It is recommended that the user apply the optimal RT value given in Table 1 for the input and output operating condition. System level or other considerations, however, may necessitate another operating frequency. While the LTM8003 is flexible enough to accommodate a wide range of operating frequencies, a haphazardly chosen one may result in undesirable operation under certain operating or fault conditions. A frequency that is too high can reduce efficiency, generate excessive heat or even damage the LTM8003 if the output is overloaded or short-circuited. A frequency that is too low can result in a final design that has too much output ripple or too large of an output capacitor. 

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LTM8003 

## **APPLICATIONS INFORMATION** 

## **BIAS Pin Considerations** 

The BIAS pin is used to provide drive power for the internal power switching stage and operate other internal circuitry. For proper operation, it must be powered by at least 3.2V. If the output voltage is programmed to 3.2V or higher, BIAS may be simply tied to VOUT. If VOUT is less than 3.2V, BIAS can be tied to VIN or some other voltage source. If the BIAS pin voltage is too high, the efficiency of the LTM8003 may suffer. The optimum BIAS voltage is dependent upon many factors, such as load current, input voltage, output voltage and switching frequency. In all cases, ensure that the maximum voltage at the BIAS pin is less than 19V. If BIAS power is applied from a remote or noisy voltage source, it may be necessary to apply a decoupling capacitor locally to the pin. A 1µF ceramic capacitor works well. The BIAS pin may also be left open at the cost of a small degradation in efficiency. If unused or generating a negative output, tie BIAS to LTM8003 GND. 

## **Maximum Load** 

The maximum practical continuous load that the LTM8003 can drive, while rated at 3.5A, actually depends upon both the internal current limit and the internal temperature. The internal current limit is designed to prevent damage to the LTM8003 in the case of overload or short-circuit. The internal temperature of the LTM8003 depends upon operating conditions such as the ambient temperature, the power delivered, and the heat sinking capability of the system. For example, if the LTM8003H is configured to regulate at 1.2V, it may continuously deliver 6A from 12VIN if the ambient temperature is controlled to less than 50°C. This is quite a bit higher than the 3.5A continuous rating. Please see the “Derating, H-Grade, VOUT = 1.2V” curve in the Typical Performance Characteristics section. Similarly, if the output voltage is 18V and the ambient temperature is 100°C, the LTM8003H will deliver at most 2.7A from 24VIN, which is less than the 3.5A continuous rating. 

## **Load Sharing** 

Neither the LTM8003 nor LTM8003-3.3 are designed to load share. 

## **Burst Mode Operation** 

To enhance efficiency at light loads, the LTM8003 automatically switches to Burst Mode operation which keeps the output capacitor charged to the proper voltage while minimizing the input quiescent current. During Burst Mode operation, the LTM8003 delivers single cycle bursts of current to the output capacitor followed by sleep periods where most of the internal circuitry is powered off and energy is delivered to the load by the output capacitor. During the sleep time, VIN and BIAS quiescent currents are greatly reduced, so, as the load current decreases towards a no load condition, the percentage of time that the LTM8003 operates in sleep mode increases and the average input current is greatly reduced, resulting in higher light load efficiency. 

Burst Mode operation is enabled by tying SYNC to GND. 

## **Minimum Input Voltage** 

The LTM8003 is a step-down converter, so a minimum amount of headroom is required to keep the output in regulation. Keep the input above 3.4V to ensure proper operation. Voltage transients or ripple valleys that cause the input to fall below 3.4V may turn off the LTM8003. 

## **Output Voltage Tracking and Soft-Start** 

The LTM8003 allows the user to adjust its output voltage ramp rate by means of the TR/SS pin. An internal 2μA pulls up the TR/SS pin to about 2.4V. Putting an external capacitor on TR/SS enables soft starting the output to reduce current surges on the input supply. During the soft-start ramp the output voltage will proportionally track the TR/ SS pin voltage. For output tracking applications, TR/SS can be externally driven by another voltage source. From 0V to 0.97V, the TR/SS voltage will override the internal 0.97V reference input to the error amplifier, thus regulating the FB pin voltage to that of the TR/SS pin. When TR/ SS is above 0.97V, tracking is disabled and the feedback voltage will regulate to the internal reference voltage. The TR/SS pin may be left floating if the function is not needed. 

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LTM8003 

## **APPLICATIONS INFORMATION** 

An active pull-down circuit is connected to the TR/SS pin which will discharge the external soft-start capacitor in the case of fault conditions and restart the ramp when the faults are cleared. Fault conditions that clear the soft-start capacitor are the RUN pin transitioning low, VIN voltage falling too low, or thermal shutdown. 

## **Pre-Biased Output** 

As discussed in the Output Voltage Tracking and SoftStart section, the LTM8003 regulates the output to the FB voltage determined by the TR/SS pin whenever TR/ SS is less than 0.97V. If the LTM8003 output is higher than the target output voltage, the LTM8003 will attempt to regulate the output to the target voltage by returning a small amount of energy back to the input supply. If there is nothing loading the input supply, its voltage may rise. Take care that it does not rise so high that the input voltage exceeds the absolute maximum rating of the LTM8003. 

## **Frequency Foldback** 

The LTM8003 is equipped with frequency foldback which acts to reduce the thermal and energy stress on the internal power elements during a short circuit or output overload condition. If the LTM8003 detects that the output has fallen out of regulation, the switching frequency is reduced as a function of how far the output is below the target voltage. This in turn limits the amount of energy that can be delivered to the load under fault. During the start-up time, frequency foldback is also active to limit the energy delivered to the potentially large output capacitance of the load. When a clock is applied to the SYNC pin, the SYNC pin is floated or held high, the frequency foldback is disabled, and the switching frequency will slow down only during overcurrent conditions. 

## **Synchronization** 

To select low ripple Burst Mode operation, tie the SYNC pin below about 0.4V (this can be ground or a logic low output). To synchronize the LTM8003 oscillator to an external frequency, connect a square wave (with about 

20% to 80% duty cycle) to the SYNC pin. The square wave amplitude should have valleys that are below 0.4V and peaks above 1.5V. 

The LTM8003 will not enter Burst Mode operation at low output loads while synchronized to an external clock, but instead will pulse skip to maintain regulation. The LTM8003 may be synchronized over a 200kHz to 3MHz range. The RT resistor should be chosen to set the switching frequency equal to or below the lowest synchronization input. For example, if the synchronization signal will be 500kHz and higher, the RT should be selected for 500kHz. 

For some applications it is desirable for the LTM8003 to operate in pulse-skipping mode, offering two major differences from Burst Mode operation. The first is that the clock stays awake at all times and all switching cycles are aligned to the clock. The second is that full switching frequency is reached at lower output load than in Burst Mode operation. These two differences come at the expense of increased quiescent current. To enable pulse-skipping mode, the SYNC pin is floated. 

The LTM8003 features spread spectrum operation to further reduce EMI/EMC emissions. To enable spread spectrum operation, apply between 2.9V and 4.2V to the SYNC pin. In this mode, triangular frequency modulation is used to vary the switching frequency between the value programmed by RT to about 20% higher than that value. The modulation frequency is about 3kHz. For example, when the LTM8003 is programmed to 2MHz, the frequency will vary from 2MHz to 2.4MHz at a 3kHz rate. When spread spectrum operation is selected, Burst Mode operation is disabled, and the part will run in pulse-skipping mode. 

The LTM8003 does not operate in forced continuous mode regardless of SYNC signal. 

## **Negative Output** 

The LTM8003 is capable of generating a negative output voltage by connecting its VOUT to system GND and the LTM8003 GND to the negative voltage rail. An example of this is shown in the Typical Applications section. The 

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LTM8003 

## **APPLICATIONS INFORMATION** 

most versatile way to generate a negative output is to use a dedicated regulator that was designed to generate a negative voltage, but using a buck regulator like the LTM8003 to generate a negative voltage is a simple and cost effective solution, as long as certain restrictions are kept in mind. 

**==> picture [149 x 106] intentionally omitted <==**

**----- Start of picture text -----**<br>
VIN<br>VIN VOUT<br>LTM8003<br>GND<br>NEGATIVE<br>OUTPUT VOLTAGE<br>8003 F01<br>**----- End of picture text -----**<br>


**Figure 1. The LTM8003 Can Be Used to Generate a Negative Voltage** 

Figure 1 shows a typical negative output voltage application. Note that LTM8003 VOUT is tied to system GND and input power is applied from VIN to LTM8003 VOUT. As a result, the LTM8003 is not behaving as a true buck regulator, and the maximum output current depends upon the input voltage. In the example shown in the Typical Applications section, there is an attending graph that shows how much current the LTM8003 can deliver for given input voltages. 

**==> picture [188 x 106] intentionally omitted <==**

**----- Start of picture text -----**<br>
VIN<br>VIN VOUT<br>LTM8003<br>GND FAST LOAD<br>TRANSIENT<br>8003 F02 OUTPUT TRANSIENT<br>RESPONSE<br>**----- End of picture text -----**<br>


**Figure 2. Any Output Voltage Transient Appears on LTM8003 GND** 

Note that this configuration requires that any load current transient will directly impress the transient voltage onto the LTM8003 GND, as shown in Figure 2, so fast load transients can disrupt the LTM8003’s operation or even cause damage. 

**==> picture [221 x 133] intentionally omitted <==**

**----- Start of picture text -----**<br>
FAST VIN<br>TRANSIENT<br>VIN OUTPUT EXPERIENCESA POSITIVE TRANSIENT<br>VIN VOUT<br>LTM8003<br>CIN COUT<br>GND<br>AC DIVIDER OPTIONAL<br>SCHOTTKY<br>DIODE<br>8003 F03<br>**----- End of picture text -----**<br>


**Figure 3. A Schottky Diode Can Limit the Transient Caused by a Fast Rising VIN to Safe Levels** 

The CIN and COUT capacitors in Figure 3 form an AC divider at the negative output voltage node. If VIN is hot-plugged or rises quickly, the resultant VOUT will be a positive transient, which may be unhealthy for the application load. An anti-parallel Schottky diode may be able to prevent this positive transient from damaging the load. The location of this Schottky diode is important. For example, in a system where the LTM8003 is far away from the load, placing the Schottky diode closest to the most sensitive load component may be the best design choice. Carefully evaluate whether the negative buck configuration is suitable for the application. When generating a negative output voltage, tie BIAS to LTM8003 GND. 

## **Shorted Input Protection** 

Care needs to be taken in systems where the output is held high when the input to the LTM8003 is absent. This may occur in battery charging applications or in battery backup systems where a battery or some other supply is diode ORed with the LTM8003’s output. If the VIN pin is allowed to float and the RUN pin is held high (either by a logic signal or because it is tied to VIN), then the LTM8003’s internal circuitry pulls its quiescent current through its internal power switch. This is fine if your system can tolerate a few milliamps in this state. If you ground the RUN pin, the internal current drops to essentially zero. However, if the VIN pin is grounded while the output is held high, parasitic 

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LTM8003 

## **APPLICATIONS INFORMATION** 

diodes inside the LTM8003 can pull large currents from the output through the VIN pin. Figure 4 shows a circuit that runs only when the input voltage is present and that protects against a shorted or reversed input. 

**==> picture [148 x 76] intentionally omitted <==**

**----- Start of picture text -----**<br>
VIN VIN<br>LTM8003<br>RUN<br>8003 F04<br>**----- End of picture text -----**<br>


**Figure 4. The Input Diode Prevents a Shorted Input from Discharging a Backup Battery Tied to the Output. It Also Protects the Circuit from a Reversed Input. The LTM8003 Runs Only When the Input Is Present** 

## **PCB Layout** 

Most of the headaches associated with PCB layout have been alleviated or even eliminated by the high level of integration of the LTM8003. The LTM8003 is nevertheless a switching power supply, and care must be taken to minimize EMI and ensure proper operation. Even with the high level of integration, you may fail to achieve specified operation with a haphazard or poor layout. See Figure 5 for a suggested layout. Ensure that the grounding and heat sinking are acceptable. 

A few rules to keep in mind are: 

1. Place CFF, RFB and RT as close as possible to their respective pins. 

2. Place the CIN capacitor as close as possible to the VIN and GND connection of the LTM8003. 

3. Place the COUT capacitor as close as possible to the VOUT and GND connection of the LTM8003. 

4. Place the CIN and COUT capacitors such that their ground current flow directly adjacent to or underneath the LTM8003. 

5. Connect all of the GND connections to as large a copper pour or plane area as possible on the top layer. Avoid breaking the ground connection between the external components and the LTM8003. 

6. Use vias to connect the GND copper area to the board’s internal ground planes. Liberally distribute these GND vias to provide both a good ground connection and thermal path to the internal planes of the printed circuit board. Pay attention to the location and density of the thermal vias in Figure 5. The LTM8003 can benefit from the heat-sinking afforded by vias that connect to internal GND planes at these locations, due to their proximity to internal power handling components. The optimum 

**==> picture [242 x 178] intentionally omitted <==**

**----- Start of picture text -----**<br>
CIN GND<br>RUN<br>VIN<br>RT<br>TR/SS COUT<br>SYNC<br>PG VOUT<br>FB BIAS<br>GND/ THERMAL VIAS<br>8003 F05<br>**----- End of picture text -----**<br>


**Figure 5. Layout Showing Suggested External Components, GND Plane and Thermal Vias** 

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## **APPLICATIONS INFORMATION** 

number of thermal vias depends upon the printed circuit board design. For example, a board might use very small via holes. It should employ more thermal vias than a board that uses larger holes. 

## **Hot-Plugging Safely** 

The small size, robustness and low impedance of ceramic capacitors make them an attractive option for the input bypass capacitor of LTM8003. However, these capacitors can cause problems if the LTM8003 is plugged into a live supply (see Linear Technology Application Note 88 for a complete discussion). The low loss ceramic capacitor combined with stray inductance in series with the power source forms an underdamped tank circuit, and the voltage at the VIN pin of the LTM8003 can ring to more than twice the nominal input voltage, possibly exceeding the LTM8003’s rating and damaging the part. If the input supply is poorly controlled or the LTM8003 is hot-plugged into an energized supply, the input network should be designed to prevent this overshoot. This can be accomplished by installing a small resistor in series to VIN, but the most popular method of controlling input voltage overshoot is add an electrolytic bulk cap to the VIN net. This capacitor’s relatively high equivalent series resistance damps the circuit and eliminates the voltage overshoot. The extra capacitor improves low frequency ripple filtering and can slightly improve the efficiency of the circuit, though it is likely to be the largest component in the circuit. 

## **Thermal Considerations** 

The LTM8003 output current may need to be derated if it is required to operate in a high ambient temperature. The amount of current derating is dependent upon the input voltage, output power and ambient temperature. The derating curves given in the Typical Performance Characteristics section can be used as a guide. These curves were generated by the LTM8003 mounted to a 58cm[2] 4-layer FR4 printed circuit board. Boards of other sizes 

and layer count can exhibit different thermal behavior, so it is incumbent upon the user to verify proper operation over the intended system’s line, load and environmental operating conditions. 

For increased accuracy and fidelity to the actual application, many designers use FEA (Finite Element Analysis) to predict thermal performance. To that end, Page 2 of the data sheet typically gives four thermal coefficients: 

θJA – Thermal resistance from junction to ambient 

- θJCbottom – Thermal resistance from junction to the bottom of the product case 

- θJCtop – Thermal resistance from junction to top of the product case 

- θJB – Thermal resistance from junction to the printed circuit board. 

While the meaning of each of these coefficients may seem to be intuitive, JEDEC has defined each to avoid confusion and inconsistency. These definitions are given in JESD 51-12, and are quoted or paraphrased below: 

θJA is the natural convection junction-to-ambient air thermal resistance measured in a one cubic foot sealed enclosure. This environment is sometimes referred to as “still air” although natural convection causes the air to move. This value is determined with the part mounted to a JESD 51-9 defined test board, which does not reflect an actual application or viable operating condition. 

θJCbottom is the junction-to-board thermal resistance with all of the component power dissipation flowing through the bottom of the package. In the typical µModule regulator, the bulk of the heat flows out the bottom of the package, but there is always heat flow out into the ambient environment. As a result, this thermal resistance value may be useful for comparing packages but the test conditions don’t generally match the user’s application. 

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LTM8003 

## **APPLICATIONS INFORMATION** 

θJCtop is determined with nearly all of the component power dissipation flowing through the top of the package. As the electrical connections of the typical µModule regulator are on the bottom of the package, it is rare for an application to operate such that most of the heat flows from the junction to the top of the part. As in the case of θJCbottom, this value may be useful for comparing packages but the test conditions don’t generally match the user’s application. 

θJB is the junction-to-board thermal resistance where almost all of the heat flows through the bottom of the µModule regulator and into the board, and is really the sum of the θJCbottom and the thermal resistance of the bottom of the part through the solder joints and through a portion of the board. The board temperature is measured a specified distance from the package, using a two sided, two layer board. This board is described in JESD 51-9. 

Given these definitions, it should now be apparent that none of these thermal coefficients reflects an actual physical operating condition of a µModule regulator. Thus, none of them can be individually used to accurately predict the 

thermal performance of the product. Likewise, it would be inappropriate to attempt to use any one coefficient to correlate to the junction temperature vs load graphs given in the product’s data sheet. The only appropriate way to use the coefficients is when running a detailed thermal analysis, such as FEA, which considers all of the thermal resistances simultaneously. 

A graphical representation of these thermal resistances is given in Figure 6. The blue resistances are contained within the µModule regulator, and the green are outside. 

The die temperature of the LTM8003 must be lower than the maximum rating, so care should be taken in the layout of the circuit to ensure good heat sinking of the LTM8003. The bulk of the heat flow out of the LTM8003 is through the bottom of the package and the pads into the printed circuit board. Consequently a poor printed circuit board design can cause excessive heating, resulting in impaired performance or reliability. Please refer to the PCB Layout section for printed circuit board design suggestions. 

**==> picture [395 x 164] intentionally omitted <==**

**----- Start of picture text -----**<br>
JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD)<br>JUNCTION-TO-CASE (TOP) CASE (TOP)-TO-AMBIENT<br>RESISTANCE RESISTANCE<br>JUNCTION-TO-BOARD RESISTANCE<br>JUNCTION AMBIENT<br>JUNCTION-TO-CASE CASE (BOTTOM)-TO-BOARD BOARD-TO-AMBIENT<br>(BOTTOM) RESISTANCE RESISTANCE RESISTANCE<br>8003 F06<br>µMODULE DEVICE<br>**----- End of picture text -----**<br>


**Figure 6. Graphical Representation of the Thermal Resistances Between the Device Junction and Ambient** 

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## **APPLICATIONS INFORMATION** 

## **Fault Tolerance** 

The fixed output version of LTM8003 is designed to tolerate a single fault condition. Shorting two adjacent pins together or leaving one single pin floating does not raise VOUT or cause damage to the LTM8003 µModule regulator. 

Table 2 describe the effects that result from shorting adjacent pins. Note that, since all pins are redundant, there is no analysis describing what happens when a single pin opens. The NC pins must be left floating to ensure fault tolerance. 

**Table 3. Table 2.  FMEA Analysis — Adjacent Pin Short Test** 

|**PIN NAME**|**HEAT**|**SMOKE**|**EFFECT**|
|---|---|---|---|
|VIN–NC|NO|NO|Circuit behaves normally.|
|VIN–RUN|NO|NO|Circuit behaves normally.|
|RUN–NC|NO|NO|Circuit behaves normally.|
|RUN–RT|NO|NO|VOUTfalls to 0V. Device can be damaged if EN/UV voltage is higher than RT ABS MAX.|
|RUN–GND|NO|NO|Vout falls to 0V.|
|RT–GND|NO|NO|SW frequency increases. VOUTmay fall below regulation voltage.|
|RT–GND BANK1|NO|NO|SW frequency increases. VOUTmay fall below regulation voltage.|
|RT–TRSS|NO|NO|VOUTwill fall below regulation voltage.|
|TR/SS–SYNC|NO|NO|VOUTwill fall below regulation voltage.|
|TR/SS–GND BANK1|NO|NO|VOUTwill fall below regulation voltage.|
|SYNC–GND|NO|NO|Circuit behaves normally.|
|SYNC–PG|NO|NO|Circuit behaves normally.|
|SYNC–GND BANK1|NO|NO|Circuit behaves normally.|
|BIAS–GND BANK1|NO|NO|Efficiency may decrease.|
|BIAS–VOUTBANK3|NO|NO|Efficiency may decrease.  If BIAS is tied to a voltage source > VOUT, VOUTmay rise.<br>If BIAS is tied to a votlage source < VOUT, VOUTmay be reduced.|
|VOUTBANK3–GND BANK1|NO|NO|VOUTwill fall to 0V.|



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LTM8003 

## **TYPICAL APPLICATIONS** 

## **3.3VOUT from 5VIN to 40VIN Step-Down Converter. BIAS Is Tied to VOUT** 

**==> picture [234 x 88] intentionally omitted <==**

**----- Start of picture text -----**<br>
VIN VIN LTM8003-3.3<br>5V TO 40V<br>RUN<br>4.7µF VOUT VOUT<br>3.3V<br>RT BIAS 4A<br>49.9k 100µF<br>850kHz GND SYNC<br>8003 TA02<br>**----- End of picture text -----**<br>


PINS NOT USED IN THIS CIRCUIT: TR/SS, PG 

## **1.2VOUT from 3.4VIN to 40VIN Step-Down Converter. BIAS Is Tied to an External 3.3V Source** 

**==> picture [280 x 89] intentionally omitted <==**

**----- Start of picture text -----**<br>
VIN VIN LTM8003<br>3.4V TO 40V<br>RUN BIAS 3.3V<br>4.7µF VOUT VOUT<br>1.2V<br>RT 47pF 100µF×2 4A<br>78.7k 402k<br>550kHz GND SYNC FB<br>8003 TA03<br>**----- End of picture text -----**<br>


PINS NOT USED IN THIS CIRCUIT: TR/SS, PG 

## **2.5VOUT from 5.5VIN to 15VIN Step-Down Converter. BIAS Is Tied to VIN** 

**==> picture [270 x 88] intentionally omitted <==**

**----- Start of picture text -----**<br>
VIN VIN LTM8003<br>5.5V TO 15V<br>BIAS<br>RUN<br>4.7µF VOUT 2.5VVOUT<br>4A<br>100µF<br>RT 63.4k<br>56.2k GND SYNC FB<br>750kHz 8003 TA04<br>**----- End of picture text -----**<br>


PINS NOT USED IN THIS CIRCUIT: TR/SS, PG 

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LTM8003 

## **TYPICAL APPLICATIONS** 

**–5VOUT from 5VIN to 35VIN Positive to Negative Converter, BIAS tied to LTM8003 GND** 

**==> picture [291 x 132] intentionally omitted <==**

**----- Start of picture text -----**<br>
INPUT BULK CAP<br>VIN<br>5V TO 35V<br>VIN LTM8003<br>—_ RUN<br>OPTIONAL<br>4.7µF VOUT SCHOTTKY<br>DIODE<br>RT FB 47µF<br>41.2k BIAS GND SYNC 24.3k<br>1MHz<br>VOUT<br>8003 TA05a –5V<br>PINS NOT USED IN THIS CIRCUIT: TR/SS, PG<br>+<br>**----- End of picture text -----**<br>


**==> picture [122 x 19] intentionally omitted <==**

**----- Start of picture text -----**<br>
Maximum Load Current vs VIN.<br>BIAS Tied to LTM8003 GND<br>**----- End of picture text -----**<br>


**==> picture [155 x 160] intentionally omitted <==**

**----- Start of picture text -----**<br>
6<br>5<br>Ft ff<br>4<br>3 fo<br>2<br>1<br>0<br>0 10 20 30 40<br>INPUT VOLTAGE (V)<br>8003 TA05b<br>MAXIMUM LOAD CURRENT (A)<br>**----- End of picture text -----**<br>


## **PACKAGE PHOTO** 

## **PACKAGE DESCRIPTION** 

## **Table 4** 

|**Table 4**||||||||
|---|---|---|---|---|---|---|---|
|**LTM8003 Pinout(Adjustable Version, Sorted by Pin Number)**||||||||
|**PIN PIN NAME**<br>**PIN PIN NAME**<br>**PIN PIN NAME**<br>**PIN PIN NAME**<br>**PIN PIN NAME**<br>A<br>1<br>GND<br>B<br>1<br>PG<br>C<br>1<br>PG<br>D<br>1<br>GND<br>E<br>1<br>A<br>2<br>SYNC<br>B<br>2<br>SYNC<br>C<br>2<br>GND<br>D<br>2<br>GND<br>E<br>2<br>A<br>3<br>SS<br>B<br>3<br>SS<br>C<br>3<br>GND<br>D<br>3<br>GND<br>E<br>3<br>A<br>4<br>RT<br>B<br>4<br>GND<br>C<br>4<br>GND<br>D<br>4<br>GND<br>E<br>4<br>A<br>5<br>RT<br>B<br>5<br>RUN<br>C<br>5<br>NC<br>D<br>5<br>NC<br>E<br>5<br>A<br>6<br>GND<br>B<br>6<br>RUN<br>C<br>6<br>VIN<br>D<br>6<br>VIN<br>E<br>6<br>~~ed~~<br>~~rd~~<br>~~Gs(GU~~<br>~~Pi;~~<br>~~ET~~<br>~~pf;~~<br>~~CUT TT~~<br>~~pf;~~<br>~~CUT TT~~<br>~~pf;~~<br>~~CUT TT~~<br>~~pf;~~<br>~~CUT TT~~<br>~~Pp;~~<br>~~CUE TT~~|**PIN PIN NAME**<br>GND<br>GND<br>GND<br>GND<br>NC<br>NC|**PIN PIN NAME**<br>F<br>1<br>F<br>2<br>F<br>3<br>F<br>4<br>F<br>5<br>F<br>6|**PIN PIN NAME**<br>FB<br>FB<br>GND<br>GND<br>GND<br>GND|**PIN PIN NAME**<br>G<br>1<br>G<br>2<br>G<br>3<br>G<br>4<br>G<br>5<br>G<br>6|**PIN PIN NAME**<br>BIAS<br>BIAS<br>VOUT<br>VOUT<br>VOUT<br>VOUT|**PIN PIN NAME**<br>H<br>1<br>H<br>2<br>H<br>3<br>H<br>4<br>H<br>5<br>H<br>6|**PIN PIN NAME**<br>VOUT<br>VOUT<br>VOUT<br>VOUT<br>VOUT<br>VOUT|
|**LTM8003 Pinout(Fixed Output Voltage, Sorted by Pin Number)**||||||||
|**PIN PIN NAME**<br>**PIN PIN NAME**<br>**PIN PIN NAME**<br>**PIN PIN NAME**<br>**PIN PIN NAME**<br>A<br>1<br>GND<br>B<br>1<br>PG<br>C<br>1<br>PG<br>D<br>1<br>GND<br>E<br>1<br>A<br>2<br>SYNC<br>B<br>2<br>SYNC<br>C<br>2<br>GND<br>D<br>2<br>GND<br>E<br>2<br>A<br>3<br>SS<br>B<br>3<br>SS<br>C<br>3<br>GND<br>D<br>3<br>GND<br>E<br>3<br>A<br>4<br>RT<br>B<br>4<br>GND<br>C<br>4<br>GND<br>D<br>4<br>GND<br>E<br>4<br>A<br>5<br>RT<br>B<br>5<br>RUN<br>C<br>5<br>NC<br>D<br>5<br>NC<br>E<br>5<br>A<br>6<br>GND<br>B<br>6<br>RUN<br>C<br>6<br>VIN<br>D<br>6<br>VIN<br>E<br>6<br>~~es ee~~<br>~~QsGG~~<br>~~Pp;~~<br>~~CE TT~~<br>~~Pp;~~<br>~~CE TT~~<br>~~Pp;~~<br>~~UE TE~~<br>~~Pp;~~<br>~~UE TE~~<br>~~Pp;~~<br>~~UE TT~~<br>~~Pp;~~<br>~~CUT TT~~<br>~~J~~|**PIN PIN NAME**<br>**PIN PIN NAME**<br>GND<br>F<br>1<br>GND<br>F<br>2<br>GND<br>F<br>3<br>GND<br>F<br>4<br>NC<br>F<br>5<br>NC<br>F<br>6<br>~~OU~~||**PIN PIN NAME**<br>GND<br>GND<br>GND<br>GND<br>GND<br>GND|**PIN PIN NAME**<br>G<br>1<br>G<br>2<br>G<br>3<br>G<br>4<br>G<br>5<br>G<br>6|**PIN PIN NAME**<br>BIAS<br>BIAS<br>VOUT<br>VOUT<br>VOUT<br>VOUT|**PIN PIN NAME**<br>H<br>1<br>H<br>2<br>H<br>3<br>H<br>4<br>H<br>5<br>H<br>6|Rev E<br>**PIN PIN NAME**<br>VOUT<br>VOUT<br>VOUT<br>VOUT<br>VOUT<br>VOUT|



27 

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LTM8003 

## **PACKAGE DESCRIPTION** 

**==> picture [518 x 633] intentionally omitted <==**

**----- Start of picture text -----**<br>
Rev E<br>6<br>SEE NOTES 3<br>PIN 1<br>A B C D E F G H SEE NOTES BGA 48 0517 REV B<br>1<br>2<br>DETAIL A<br>e<br>3<br>G<br>4<br>5 b<br>PACKAGE BOTTOM VIEW µModule<br>6 LTMXXXXXX<br>PACKAGE IN TRAY LOADING ORIENTATION<br>PACKAGE ROW AND COLUMN LABELING MAY VARY  AMONG µModule PRODUCTS. REVIEW EACH PACKAGE  LAYOUT CAREFULLY<br>b e !<br>DETAILS OF PIN #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PIN #1 IDENTIFIER MAY BE EITHER A MOLD OR  MARKED FEATURE<br>F<br>NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 2. ALL DIMENSIONS ARE IN MILLIMETERS 3        BALL DESIGNATION PER JEP95 4 5. PRIMARY DATUM -Z- IS SEATING PLANE 6 COMPONENT PIN “A1” TRAY PIN 1 BEVEL<br>3.32mm)<br>×<br>A A2<br>DETAIL B<br>6.25mm  NOTES BALL HT BALL DIMENSION PAD DIMENSION SUBSTRATE THK MOLD CAP HT<br>× PACKAGE SIDE VIEW<br>BGA Package<br>MAX 3.52 0.60 2.92 0.70 0.53 0.37 2.55 0.15 0.10 0.20 0.25 0.10<br>Y<br>A1 SUBSTRATE H1 MXZ MZ<br>ddd eee DIMENSIONS NOM 3.32 0.50 2.82 0.60 0.50 9.00 6.25 1.00 7.00 5.00 0.32 2.50<br>48-Lead (9mm (Reference LTC DWG # 05-08-1999 Rev B) b1<br>H2<br>ccc  Z MOLD CAP DETAIL B DETAIL A MIN 3.12 0.40 2.72 0.50 0.47 0.27 2.45 TOTAL NUMBER OF BALLS: 48<br>Øb (48 PLACES)<br>A A1 A2 b b1 D E e F G H1 H2 aaa bbb ccc ddd eee<br>SYMBOL<br>aaa  Z<br>D X 3.5 2.5 1.5 0.5 0.000 0.5 1.5 2.5 3.5<br>Y<br>E<br>TOP VIEW<br>PACKAGE TOP VIEW<br>SUGGESTED PCB LAYOUT<br>4<br>PIN “A1” CORNER<br>0.50 ±0.025 Ø 48x<br>Z<br>Z<br>Z//  bbb<br>2.5<br>1.5<br>0.5<br>0.000<br>0.5<br>1.5<br>2.5<br>aaa  Z<br>**----- End of picture text -----**<br>


28 

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LTM8003 

## **REVISION HISTORY** 

|**REV**|**DATE**|**DESCRIPTION**|**PAGE NUMBER**|
|---|---|---|---|
|A|2/17|Added “Silent Switcher” to product description and features.<br>Added EMI performance graph.<br>Added Fault Tolerance section and FMEA analysis table.|1<br>13, 14<br>25|
|B|5/17|Added LTM8003IY and LTM8003HY.<br>Changed recommended BIAS pin connection from Open to GND for negative output applications.|2<br>5, 7, 11, 13, 14,<br>17, 19, 21, 27|
|C|12/17|Changed Peak Reflow Body Temperature from 260°C to 250°C.|2|
|D|7/18|Corrected graph title on p27 from Bias Open to Bias Tied to LTM8003 GND.|27|
|E|9/18|Corrected part numbers on the Order Information table:<br>LTM8003-3.3IY#PBF to LTM8003IY-3.3#PBF<br>LTM8003-3.3HY#PBF to LTM8003HY-3.3#PBF<br>Updated package thermal resistance:<br>JA= 23.5°C/W toJA= 24.7°C/W,JCbottom= 3.2°C/W toJCbottom= 4.5°C/W<br>JCtop= 17.9°C/W toJCtop= 22.3°C/W,JB= 3.1°C/W toJB= 4.2°C/W<br>Changed recommended BIAS voltage from 5 to, 3.2 to 19 on Table 1|2<br>2<br>17|



Rev E 

29 

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implicatiFor more informati **on** or otherwise under any patent or patent rights of Analog Devices.www.analog.com 

LTM8003 

## **TYPICAL APPLICATION** 

**0.97VOUT from 3.4VIN to 40VIN Step Down Converter with Spread Spectrum. BIAS is Tied to an External 3.3V Source** 

**==> picture [276 x 93] intentionally omitted <==**

**----- Start of picture text -----**<br>
VIN VIN LTM8003<br>3.4V TO 40V<br>RUN<br>4.7µF VOUT VOUT<br>0.97V<br>RT 47pF 100µF 4A<br>84k FB ×2<br>450kHz GND SYNC BIAS 8003 TA06<br>; Ee<br>EXTERNAL<br>3.3V<br>**----- End of picture text -----**<br>


PINS NOT USED IN THIS CIRCUIT: TR/SS, PG 

## **DESIGN RESOURCES** 

|**DESIGN RESOURCES**|||
|---|---|---|
|**SUBJECT**|**DESCRIPTION**||
|µModule Design and Manufacturing Resources|Design:<br>• Selector Guides<br>• Demo Boards and Gerber Files<br>• Free Simulation Tools|Manufacturing:<br>• Quick Start Guide<br>• PCB Design, Assembly and Manufacturing Guidelines<br>• Package and Board Level Reliability|
|µModule Regulator Products Search|1.  Sort table of products by parameters and download the result as a spread sheet.<br>2. Search using the Quick Power Search parametric table.<br>INPUT |<br>Vin(Min)<br>Vv<br>Vin(Max)<br>Vv<br>OUTPUT |<br>Vout<br>Vv<br>lout<br>A<br>FEATURES |<br>Low EMI<br>Ultrathin<br>Internal Heat Sink||
|Digital Power System Management|Analog Devices’ family of digital power supply management ICs are highly integrated solutions that<br>offer essential functions, including power supply monitoring, supervision, margining and sequencing,<br>and feature EEPROM for storing user configurations and fault logging.||



## **RELATED PARTS** 

|**PART NUMBER **|**DESCRIPTION**|**COMMENTS**|
|---|---|---|
|LTM8002|Lower Current of LTM8003. 40V, 2.5A Step-Down<br>Silent Switcher µModule Regulator with FMEA<br>Compliant Pinout|3.4V ≤ VIN≤ 40V, 0.97V ≤ VOUT≤ 18V, 6.25mm × 6.25mm × 2.22mm BGA<br>Package|
|LTM8053|40V, 3.5A Step-Down Silent Switcher µModule Regulator|3.4V ≤ VIN≤ 40V, 0.97V ≤ VOUT≤ 15V, 6.25mm × 9mm × 3.32mm BGA Package|
|LTM8063|40V, 2A Step-Down Silent Switcher µModule Regulator|3.2V ≤ VIN≤ 40V, 0.8V ≤ VOUT≤ 15V, 4mm × 6.25mm × 2.22mm BGA Package|
|LTM8065|40V, 2.5A Step-Down Silent Switcher µModule Regulator|3.4V ≤ VIN≤ 40V, 0.97V ≤ VOUT≤ 18V, 6.25mm × 6.25mm × 2.32mm BGA<br>Package|
|LTM8032|36V, 2A Low EMI Step-Down µModule Regulator|3.6V ≤ VIN≤ 36V, 0.8V ≤ VOUT≤ 10V, EN55022B Compliant|
|LTM8033|36V, 3A Low EMI Step-Down µModule Regulator|3.6V ≤ VIN≤ 36V, 0.8V ≤ VOUT≤ 24V, EN55022B Compliant|
|LTM8026|36V, 5A CVCC Step-Down µModule Regulator|6V ≤ VIN≤ 36V, 1.2V ≤ VOUT≤ 24V, Constant Voltage Constant Current Operation|
|LTM4613|36V, 8A Low EMI Step-Down µModule Regulator|5V ≤ VIN≤ 36V, 3.3V ≤ VOUT≤ 15V, EN55022B Compliant|
|LTM8073|60V, 3A Step-Down Silent Switcher µModule Regulator|3.4V ≤ VIN≤ 60V, 0.8V ≤ VOUT≤ 15V, 6.25mm × 9mm × 3.32mm BGA Package|



Rev E 

D17129-0-9/18(E) www.analog.com 

30 

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