MP4658GS-P

_**MP4658**_ 

## **4-String, Max 200mA/Channel, 80V Return LED Driver with AC/DC Feedback** 

## **DESCRIPTION** 

The MP4658 is a 4-string, secondary-side LED driver for LED backlighting, and is ideal for monitor and small-sized TV LED backlighting. It controls the flyback power stage to regulate the LED current loop and the output supply voltage. The MP4658 integrates 4-string LED current balancing. Powered by a 6V to 36V input supply voltage (VIN), the MP4658 outputs a compensation signal to control the primary-side flyback (or other power stage) via an optocoupler to regulate the output voltage (VOUT). 

The MP4658 supports analog dimming and PWM dimming to the LED current through the ADIM and PDIM pins. For analog dimming, apply a pulse signal with a frequency above 5kHz to the ADIM pin. For PWM dimming, apply a low-frequency PWM signal to the PDIM pin. The MP4658 also supports analog mode PWM dimming to the LED current, which makes the LED current rise and fall softly. 

The MP4658 features numerous smart protections to increase system reliability, including open LED protection, short LED string protection, LEDx short-to-ground protection, FB over-voltage protection (OVP), feedback open protection, and thermal protection. The MP4658 is available in an SOIC-16 package. 

## **FEATURES** 

- 6V to 36V Supply Voltage (VIN) 

- 80V/200mA, 4-String LED Current Balance 

- Provides Feedback for the Previous Power Stage 

- <2% LED Current Accuracy 

- 1.5% LED Current Balance 

- Low LEDx Regulation Voltage, High Efficiency 

- Analog and PWM Dimming 

- LED Open Protection, LED Short Protection 

- LEDx Pin Short-to-GND Protection 

- Over-Voltage Protection (OVP) 

- Thermal Protection 

- Available in an SOIC-16 Package 

## **APPLICATIONS** 

- LCD Monitor and TVs 

- Desktop LCD Flat Panel Displays 

- Flat-Panel Video Displays 

All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For MPS green status, please visit the MPS website under Quality Assurance. “MPS”, the MPS logo, and “Simple, Easy Solutions” are trademarks of Monolithic Power Systems, Inc. or its subsidiaries. 

## **TYPICAL APPLICATION** 

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TM D1 VLED<br>Flyback<br>; C1 R1<br>85V to 265VAC 380V Bus100V to  3 NP NLED SSARS R2 1 E AEA<br>M1 - NSYS D2 Y C2 VOUT DC/DC C3 VSYS »i<br>Y R3<br>l R4<br>¢ H C4 15 VIN MP4658 FB 3 =>) R5<br>C5 R6 4 COMP2 LED1 7<br>| ControllerFlyback  oe< H C6 HS R7 5 COMP1 LED2 8<br>to R8 12 ISET OVP 6<br>R9 2 OPT GND 9<br>>5kHz 16 FF NC 14<br>ADIM 13 ADIM LED3 11<br>a] >100Hz PDIM 1 PDIM LED4 10<br>**----- End of picture text -----**<br>


**1** 

MP4658 Rev. 1.0 10/13/2021 

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MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2021 MPS. All Rights Reserved. 

**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** MPS 

## **ORDERING INFORMATION** 

|**Part Number***|**Package**|**Top Marking**|**MSL Rating**|
|---|---|---|---|
|MP4658GS|SOIC-16|_See Below_|2|



* For Tape & Reel, add suffix -Z (e.g. MP4658GS-Z). 

## **TOP MARKING** 

MPS: MPS prefix YY: Year code WW: Week code MP4658: Part number LLLLLLLLL: Lot number 

## **PACKAGE REFERENCE** 

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TOP VIEW<br>MP4658<br>1 16<br>PDIM FF<br>2 15<br>OPT VIN<br>3 14<br>FB NC<br>4 COMP2 ADIM 13<br>5 12<br>COMP1 ISET<br>6 11<br>OVP LED3<br>7 LED1 LED4 10<br>8 9<br>LED2 GND<br>**----- End of picture text -----**<br>


**SOIC-16** 

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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **PIN FUNCTIONS** 

|**Pin #**<br>~~a~~|**Name**|**Description**|
|---|---|---|
|1<br>~~ee~~|PDIM<br>|**PWM dimming input pin.**Connect a pulse signal to implement pulse-width modulation<br>(PWM) dimming. When the PDIM pin’s voltage remains low for 30ms, the LED stage is<br>disabled and the IC enters constant voltage(CV)mode.<br>|
|2<br>~~eea ~~|OPT<br> ~~a ee~~|**Optocoupler pin.**This pin outputs the compensation signal for the primary-side flyback<br>power stage. Connect thispin to the external optocoupler to control the flyback. <br>~~ee~~|
|3<br>~~a ~~|FB<br> ~~a ee~~|**System voltage feedback.**Connect this pin to the system output through a voltage<br>divider.<br>~~ee~~|
|4<br>~~a ~~|COMP2<br> ~~a ee~~|**Compensation pin.**This pin compensates the output voltage (VOUT) loop and controls the<br>flybackpower stage duringthe LED offperiod.<br>~~ee~~|
|5<br>~~aa~~|COMP1<br>~~aa~~|**Compensation pin.**This pin compensates the LED current loop and controls the flyback<br>power stage duringthe LED onperiod.<br>~~aa~~|
|6<br>~~a~~<br>~~es~~|OVP<br>~~aa~~<br>~~es~~|**Over-voltage protection (OVP) pin.**Connect this pin to the LED voltage (VLED) output<br>through a voltage divider.<br>~~ee~~<br>|
|7<br>~~a~~<br>~~es~~|LED1<br>~~aa~~<br>~~es~~|**Cathode of LED string 1.**<br>~~ee~~<br>|
|8<br><br>~~es a~~|LED2<br>~~a~~<br> ~~esa~~|**Cathode of LED string 2.**<br>~~ee~~<br>~~a~~|
|9<br>~~a~~<br>~~ee~~|GND<br>~~a~~|**Ground.**<br>~~a~~|
|10<br>~~ee~~|LED4|**Cathode of LED string 4.**|
|11<br>~~ee~~|LED3|**Cathode of LED string 3.**|
|12<br>~~ee~~<br>~~a ~~|ISET<br> ~~a ee~~|**LED current set pin.**This pin sets the LED current. Connect a resistor from this pin to the<br>ground to set the LED current(ILED).<br>~~ee~~|
|13<br>~~Ss~~|ADIM<br>~~Ss~~|**Analog dimming input pin.**Connect a >5kHz PWM signal to implement analog dimming.<br>The input impedance of this pin determines the internal filter constant, as well as the PWM<br>dimming rise and fall times. When the ADIM pin’s voltage remains low for 30ms, the LED<br>stage is disabled and the IC enters CV mode.|
|14<br>~~Ss~~<br>~~ee~~|NC<br>~~Ss~~|**Not connected.**|
|15<br>~~ee~~|VIN|**Input supply pin.**Thispinpowers all internal logic circuitry.|
|16<br>~~ee~~|FF|**Fault indicatorpin.**If a fault occurs,thispin ispulled low.|



## **ABSOLUTE MAXIMUM RATINGS**[(1)] 

VIN .............................................. -0.3V to +38V LEDx ............................................ -0.3V to +80V FF   .............................................. -0.3V to +12V Other pins ................................... -0.3V to +6.5V Junction temperature ............................... 150°C Lead temperature .................................... 260°C Continuous power dissipation (TA = 25°C)[(2)] ................................................................ 1.56W Storage temperature ................ -60°C to +150°C 

## _**ESD Ratings**_ 

Human body model (HBM) .................... ±2000V Charged device model (CDM)..................±750V 

## _**Thermal Resistance**_[(4)] _**θJA θJC**_ 

SOIC-16 ................................. 80 ...... 35 ... °C/W 

## **Notes:** 

- 1) Exceeding these ratings may damage the device. 

- 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX) - TA) / θJA. Exceeding the maximum allowable power dissipation produces an excessive die temperature, causing the regulator to go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 

- 3) The device is not guaranteed to function outside of its operating conditions. 

- 4) Measured on JESD51-7, 4-layer PCB. 

## _**Recommended Operating Conditions**_[(3)] 

Supply voltage (VIN) ........................... 6V to 36V Operating junction temp (TJ) .... -40°C to +125°C 

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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **ELECTRICAL CHARACTERISTICS** 

**VIN = 12V, TA = 25°C, unless otherwise noted.** 

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|||||||||||
|---|---|---|---|---|---|---|---|---|---|
|eG|Parameter|Symbol|GO|Condition|Min|Typ|Max|Units|
|VIN Supply|
|ee|VIN supply range|6|36|V|
|VIN UVLO|VIN_UVLO|4.5|4.79|5.5|V|
|po|ee|ee|ee|oe oe|
|VIN UVLO hysteresis|VIN_HYS_UVLO|500|mV|
|yee|Quiescent current|IQ|PWM = ADIM = 0|0.5|mA|
|Analog Dimming|
|ee|ADIM logic high|VADIM_HI|1.5|V|
|Ge|ADIM logic low|VADIM_LO|GGee|ee|ee|oe|0.4|V|
|GG|ADIM/PWM pull-down resistor|RADIM_DOWN|OO|1|MΩ|
|Analog dimming input|
|5|[(5) ]|100|[(5)]|kHz|
|a|frequency range|
|Duration to disable the ADIM|
|a|pin|tADIM_ST|30|ms|
|ADIM pin input impedance for|
|25|50|kΩ|
|a|slow soft PWM dimming|(3ms)|
|ADIM pin input impedance for|
|15|kΩ|
|a|fast soft PWM dimming|(700µs)|
|PWM Dimming|
|PDIM logic high|VPDIM_HI|1.5|V|
|pry|PDIM logic low|VPDIM_LO|0.4|V|
|PDIM pull-down resistor|RPDIM_DOWN|1|MΩ|
|py|PDIM input frequency range|100|[(5) ]|Hz|
|Duration to disable the PDIM|
|a|pin|tPDIM_ST|30|ms|
|OPT|
|Normal operation H|2.3|V|
|OPT pin output voltage range|
|Normal operation L|0.8|V|
|pe|OPT pin output voltage when|——ry——y——|
|3.3|V|
|latched off|
|a|
|eG|Source current capability|IOPT|Fe|CO|20|mA|
|VFB|
|Reference voltage|VFB_REF|PWM off|1.182|1.2|1.218|V|
|ee|FB VFB over-voltage protection pull-down resistor|RFB_DOWN|ee|ee|ee|1|ae|MΩ|
|a|(OVP)|VFB_OVP|1.24|VREF_VFB|
|System open feedback|
|a|protection|VREF_OPEN|500|mV|
|Compensation Loop for LED (COMP1)|
|Gain bandwidth product|GBCOMP1|75pF on COMP1|1|[(5)]|MHz|
|ory|Open-loop DC gain|AV_COMP1|COMP1 open|70|[(5)]|dB|
|Ge|Input common-mode range|VCM_COMP1|OG|For design|-0.3|[(5)]|+4|[(5)]|V|
|Transconductance|GM_COMP1|PWM = high|720|μA/V|
|po|

**----- End of picture text -----**<br>


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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **ELECTRICAL CHARACTERISTICS** _**(continued)**_ 

**VIN = 12V, TA = 25°C, unless otherwise noted.** 

|**Parameter**<br>~~eG~~|**Symbol**<br>~~eG~~|**Condition**<br>~~eG~~|**Min**<br>~~eG~~|**Typ**<br>~~eG~~|**Max**<br>~~eG~~|**Units**<br>~~eG~~|
|---|---|---|---|---|---|---|
|Saturated output current<br>~~ee~~|ISAT_COMP1<br>~~ee~~|~~ee~~|~~ee~~|90<br>~~ee~~|~~ee~~|μA<br>~~ee~~|
|Low-level clampvoltage<br>~~sD~~<br>~~a~~|VCOMP1_L<br>~~sD~~<br>|Normal operation<br>~~sD~~<br>|~~sD~~<br>|1<br>~~sD~~<br>|~~sD~~<br>|V<br>~~sD~~<br>|
|High-level clampvoltage<br>~~a~~|VCOMP1_H<br>|Normal operation<br>||2.5<br>||V<br>|
|**Compensation Loop for LED(COMP2)**<br>~~aes~~|||||||
|Gain bandwidthproduct<br>~~es~~|GB_COMP275<br>~~es~~|75pF on COMP2<br>~~es~~|~~es~~|1(5)<br>~~es~~|~~es~~|MHz<br>~~es~~|
|Open-loopDCgain<br>~~es~~|AV_COMP2<br>~~es~~|COMP2 open<br>~~es~~|~~es~~|70(5)<br>~~es~~|~~es~~|dB<br>~~es~~|
|Low-level clampvoltage<br>~~sD~~|VCOMP2_L<br>~~sD~~|Normal operation<br>~~sD~~|~~sD~~|1<br>~~sD~~|~~sD~~|V<br>~~sD~~|
|High-level clampvoltage<br>~~es~~<br>~~a~~|VCOMP2_H<br>~~es~~<br>~~ee~~|Normal operation<br>~~es~~<br>~~**e**e~~|~~es~~|2.5<br>~~es~~|~~es~~|V<br>~~es~~|
|Transconductance when<br>PWM is off<br>~~a~~|GM_COMP2<br>~~ee~~|PWM off<br>~~**e**e~~||260||μA/V|
|Saturated output current<br>~~a~~<br>~~e~~|ISAT_COMP2<br>~~ee~~<br>~~e~~|~~**e**e~~<br>~~e~~||45||μA|
|**LED Driver Protection(OVP, LED Open/Short)**<br>~~e~~|||||||
|OVP threshold<br>~~sD~~<br>~~——~~|VTH_OVP<br>~~sD~~<br>~~ee~~|~~sD~~<br>~~ee~~|~~sD~~<br>~~ee~~|2.4<br>~~sD~~<br>~~ee~~|~~sD~~<br>~~ee~~|V<br>~~sD~~<br>~~ee~~|
|OVP threshold hysteresis<br>~~——~~|~~ee~~|~~ee~~|~~ee~~|200<br>~~ee~~|~~ee~~|mV<br>~~ee~~|
|OVP to latch IC threshold<br>~~——~~<br>~~es~~|~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|~~ee~~|3<br>~~ee~~|~~ee~~|V<br>~~ee~~|
|LEDx threshold for open LED<br>stringmark-off<br>~~——~~<br>~~es~~<br>~~———~~|~~ee~~<br>~~ee~~<br>|OVP triggered<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>|~~ee ~~<br>|100<br> ~~ee~~<br>|~~ee ~~<br>|mV<br> ~~ee~~<br>|
|LEDx over-voltage (OV)<br>threshold (for LED short<br>protection)<br>~~es ~~<br>~~re~~<br>~~———~~<br>~~a~~|VTH_LEDxOV<br> ~~ee~~<br>~~re~~<br>~~es~~|~~ee~~<br>~~re~~<br>~~ee~~<br>~~ee~~|~~re~~<br>~~ee~~|5<br>~~re~~<br>~~ee~~|~~re~~<br>~~ee~~<br>~~ee~~|V<br>~~re~~<br>~~ee~~<br>~~ee~~|
|LED short delaytime<br>~~———~~<br>~~a~~|tD_LEDxOV<br>~~es~~|~~ee~~<br>~~ee~~|~~ee~~|5<br>~~ee~~|~~ee~~<br>~~ee~~|ms<br>~~ee~~<br>~~ee~~|
|Thermalprotection threshold<br>~~———~~<br>~~a~~|~~es~~|~~ee~~<br>~~ee~~|~~ee~~|150(5)<br>~~ee~~|~~ee~~<br>~~ee~~|°C<br>~~ee~~<br>~~ee~~|
|Thermal protection<br>hysteresis<br>~~——— ~~<br>~~a~~<br>~~———~~|~~es~~|~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|25(5)<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|°C<br>~~ee~~<br>~~ee~~|
|**LED Current Regulation(VLEDx, ISET)**<br>~~———~~<br>~~ee~~|||||||
|ISET voltage<br>~~———~~|VISET|~~ee~~|1.53<br>~~ee~~|1.58<br>~~ee~~|1.63|V|
|LEDx average current<br>~~———~~<br>~~ce~~|ILED<br>~~ce~~|RISET= 320kΩ(trim)<br>~~ee~~<br>~~ce~~|-1.5%<br>~~ee~~<br>~~ce~~|50<br>~~ee~~<br>~~ce~~|+1.5%<br>~~ce~~|mA<br>~~ce~~|
|||RISET= 320kΩ(40%)<br>~~ee~~<br>~~ce~~|-3%<br>~~ee~~<br>~~ce~~|20.3<br>~~ee~~<br>~~ce~~|+3%<br>~~ce~~|mA<br>~~ce~~|
|Current matching<br>~~ce~~<br>~~es~~<br>~~ee~~|~~ce~~<br>~~es~~<br>~~ee~~|ILED= 50mA<br>~~ce~~<br>~~es~~<br>~~ee~~|~~ce~~<br>~~es~~<br>~~ee~~|0.3<br>~~ce~~<br>~~es~~<br>~~ee~~|2<br>~~ce~~<br>~~es~~<br>~~ee~~|%<br>~~ce~~<br>~~es~~|
|~~es~~<br>~~ee~~|~~es~~<br>~~ee~~|RISET= 320kΩ, ILED= 20mA<br>(40% of ADIM)<br>~~es~~<br>~~ee~~|~~es~~<br>~~ee~~|0.4<br>~~es~~<br>~~ee~~<br>~~ee~~|2.5<br>~~es~~<br>~~ee~~<br>~~ee~~|%<br>~~es~~<br>~~ee~~|
|Minimum LEDx regulation<br>voltage<br>~~ee~~<br>~~ce~~|VLEDx<br>~~ee~~<br>~~ce~~|ILED= 200mA<br>~~ee ~~<br>~~ce~~|~~ee~~<br>~~ce~~|560<br>~~ee~~<br>~~ce~~<br>~~ee~~|~~ee~~<br>~~ce~~<br>~~ee~~|mV<br>~~ce~~<br>~~ee~~|
|||ILED= 1mA<br>~~ce~~|~~ce~~|176<br>~~ce~~<br>~~ee~~|~~ce~~<br>~~ee~~|mV<br>~~ce~~<br>~~ee~~|
|FFpinpull-down resistor<br>~~ce~~<br>~~eG~~|~~ce~~<br>~~eG~~|Open drain<br>~~ce~~<br>~~eG~~|~~ce~~<br>~~eG~~|270<br>~~ce~~<br>~~ee~~<br>~~eG~~|~~ce~~<br>~~ee~~<br>~~eG~~|Ω<br>~~ce~~<br>~~ee~~<br>~~eG~~|



## **Note:** 

5) Guaranteed by design. Not tested in production. 

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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

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Reference Voltage vs.<br>Temperature VFB OVP vs. Temperature<br>1.21 1.49<br>1.205<br>1.485<br>1.2<br>1.48<br>1.195<br>1.475<br>1.19<br>he<br>1.185 1.47<br>-50 0 50 100 -50 0 50 100<br>TEMPERATURE (°C) TEMPERATURE ( C)<br>VIN Rising Voltage vs.  VLED OVP Threshold vs.<br>Temperature Temperature<br>4.75 2.39<br>4.73 2.38<br>4.71 2.37<br>4.69 2.36<br>4.67 2.35<br>Ss]fa fosRR<br>4.65 2.34<br>-50 0 50 100 -50 0 50 100<br>TEMPERATURE ( C) TEMPERATURE ( C)<br>VFB Open Voltage vs.<br>ISET Voltage vs. Temperature<br>Temperature<br>505 1.59<br>504 1.585<br>503 1.58<br>502 1.575<br>a n<br>501 1.57<br>-50 0 50 100 -50 0 50 100<br>TEMPERATURE ( C) TEMPERATURE ( C)<br>VFB OPEN VOLTAGE (mV)<br> RISING VOLTAGE (V)<br>IN<br>V<br> (V)<br>FB_REF<br>V<br>ISET VOLTAGE (V)<br>VLED OVP THRESHOLD (V)<br> (V)<br>FB_OVP<br>V<br>**----- End of picture text -----**<br>


**ISET Voltage vs. Temperature** 

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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** MPS 

## **TYPICAL PERFORMANCE CHARACTERISTICS** _**(continued)**_ 

**Quiescent Current vs. Temperature** 

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**----- Start of picture text -----**<br>
227<br>226<br>225<br>224<br>223<br>222<br>221<br>|<br>220<br>-50 0 50 100<br>TEMPERATURE ( C)<br>OPT Low-Level Voltage vs.<br>Temperature<br>0.77<br>0.76<br>0.75<br>0.74<br>oui<br>0.73<br>-50 0 50 100<br>TEMPERATURE ( C)<br>QUIESCENT CURRENT (mA)<br>OPT LOW LEVEL VOLTAGE (V)<br>**----- End of picture text -----**<br>


## **OPT High-Level Voltage vs. Temperature** 

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**----- Start of picture text -----**<br>
2.264<br>2.262<br>2.26<br>2.258<br>2.256<br>2.254<br>2.252<br>2.25<br>2.248<br>2.246<br>2.244<br>2.242<br>-50 0 50 100<br>TEMPERATURE ( C)<br>OPT HIGH LEVEL VOLTAGE (V)<br>**----- End of picture text -----**<br>


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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **TYPICAL PERFORMANCE CHARACTERISTICS** _**(continued)**_ 

**VIN_AC = 220VAC, VLED = 40V, ILED = 80mA/string, VSYS = 5V, ISYS = 3A, TA = 25°C, unless otherwise noted.** 

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**----- Start of picture text -----**<br>
Standby Mode<br>**----- End of picture text -----**<br>


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**----- Start of picture text -----**<br>
VSYS = 5V, ISYS = 0.1A<br>CH1: VOUT<br>CH3: VSYS<br>CH2: VSW<br>CH4: VLED<br>**----- End of picture text -----**<br>


**==> picture [99 x 105] intentionally omitted <==**

**----- Start of picture text -----**<br>
CV Mode<br>CH1: VOUT<br>CH3: VSYS<br>CH2: VSW<br>CH4: VLED<br>**----- End of picture text -----**<br>


## **Power on in CV Mode** 

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**----- Start of picture text -----**<br>
Power off in CV Mode<br>**----- End of picture text -----**<br>


**==> picture [35 x 51] intentionally omitted <==**

**----- Start of picture text -----**<br>
CH1: VOUT<br>CH3: VLED<br>CH4: VSYS<br>CH2: VSW<br>**----- End of picture text -----**<br>


**==> picture [36 x 48] intentionally omitted <==**

**----- Start of picture text -----**<br>
CH1: VOUT<br>CH3: VLED<br>CH4: VSYS<br>CH2: VSW<br>**----- End of picture text -----**<br>


## **LED Enable** 

**==> picture [129 x 106] intentionally omitted <==**

**----- Start of picture text -----**<br>
50% analog dimming<br>CH1: VOUT<br>CH4: ILED<br>CH3: VLED<br>CH2: VSW<br>**----- End of picture text -----**<br>


**==> picture [36 x 54] intentionally omitted <==**

**----- Start of picture text -----**<br>
CH1: VOUT<br>CH4: ILED<br>CH3: VLED<br>CH2: VSW<br>**----- End of picture text -----**<br>


## **LED Disable** 

50% analog dimming 

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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **TYPICAL PERFORMANCE CHARACTERISTICS** _**(continued)**_ 

**VIN_AC = 220VAC, VLED = 40V, ILED = 80mA/string, VSYS = 5V, ISYS = 3A, TA = 25°C, unless otherwise noted.** 

**==> picture [91 x 108] intentionally omitted <==**

**----- Start of picture text -----**<br>
Start-Up<br>CH1: VOUT<br>CH3: VLED<br>CH4: ILED<br>CH2: VSW<br>**----- End of picture text -----**<br>


**==> picture [105 x 108] intentionally omitted <==**

**----- Start of picture text -----**<br>
Shutdown<br>CH1: VOUT<br>CH3: VLED<br>CH4: ILED<br>CH2: VSW<br>**----- End of picture text -----**<br>


## **LED On** 

100% dimming 

## **LED On** 

## 50% dimming 

**==> picture [35 x 51] intentionally omitted <==**

**----- Start of picture text -----**<br>
CH1: VOUT<br>CH2: VSW<br>CH3: VLED<br>CH4: ILED<br>**----- End of picture text -----**<br>


**==> picture [36 x 37] intentionally omitted <==**

**----- Start of picture text -----**<br>
CH1: VOUT<br>CH2: VSW<br>CH4: ILED<br>CH3: VLED<br>**----- End of picture text -----**<br>


## **One String Short** 

## **One String Open** 

**==> picture [285 x 91] intentionally omitted <==**

**----- Start of picture text -----**<br>
CH1: VOUT<br>CH4: ILED  CH1: VOUT<br>CH3: VLED CH4: ILED<br>CH2: FT CH3: VLED<br>CH2: FT<br>**----- End of picture text -----**<br>


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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **TYPICAL PERFORMANCE CHARACTERISTICS** _**(continued)**_ 

**VIN_AC = 220VAC, VLED = 40V, ILED = 80mA/string, VSYS = 5V, ISYS = 3A, TA = 25°C, unless otherwise noted.** 

**==> picture [131 x 133] intentionally omitted <==**

**----- Start of picture text -----**<br>
Load Transient<br>CH1: VOUT Paar<br>CH4: ILED<br>CH2: VCOMP1<br>CH3: ISYS<br>**----- End of picture text -----**<br>


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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## MPS 

## **FUNCTIONAL BLOCK DIAGRAM** 

**==> picture [486 x 468] intentionally omitted <==**

**----- Start of picture text -----**<br>
Delay UVLO_VIN<br>a<br>2<br>Level Adjust<br>OPT<br>— VCC 15<br>PWM PWM_N LDO VIN<br>_<br>Fault<br>7<br>PWM LED1<br>5 REF_LED LED1 IREF GM<br>COMP1 S1 Gm_I Min LEDLED32 .. 8<br>Min LEDx LED4 . LED2<br>pip TE tT .<br>4 . 11<br>COMP2 . LED3<br>EN_CHx<br>PWM_N 10<br>1.2V GM_V LED4<br>S S2 Fault [|<br>1.2 * VREF_VFB OV_LED 2.4V 6 OVP<br>3 OV VSYS OVP<br>FB Lip G e 4<br>Fault Control<br>0.5V 3V<br>Delay10µs  OVP<br>ona =<br>12<br>ISET (}—_ AdjustmentVoltage  DC ADIM Fault LED LED Protection<br>Management<br>5V<br>1 5ms<br>PWM Delay LEDx<br>PDIM : T +<br>Dimming<br>Control 100mV<br>13<br>ADIM DC ADIM LEDx<br>io n <<br>**----- End of picture text -----**<br>


**Figure 1: Functional Block Diagram** 

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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **OPERATION** 

The MP4658 is a 4-string, secondary-side LED driver for LED backlighting, and is ideal for monitor and TV LED backlighting. It controls the flyback power stage to regulate the LED current (ILED) loop during the PWM on time and regulate system supply voltage loop during the PWM off time. Powered by a 6V to 36V input voltage (VIN) supply, the MP4658 outputs a compensation signal to control the primary-side flyback (or other power stage) through an optocoupler. 

## **Start-Up** 

When the flyback is on, VIN is charged until it reaches its UVLO threshold, at which point the system logic starts to work. 

## **LED Current and Voltage Regulation** 

The MP4658 accurately regulates the ILED loop or the output voltage (VOUT) with a single flyback power stage. 

When pulse-width modulation (PWM) dimming is on, the MP4658 regulates ILED through the flyback power stage control (see Figure 2). 

**==> picture [221 x 79] intentionally omitted <==**

When PWM dimming is off, the LED stage is disabled and the MP4658 regulates the output voltage (VOUT) using the feedback (FB) voltage (VFB) from the FB pin (see Figure 3). 

**==> picture [221 x 81] intentionally omitted <==**

## _**LED Current Regulation when PWM**_ 

## _**Dimming Is On**_ 

For the ILED regulation loop, the minimum LEDx voltage (VLEDx) is fed back and compared to the internal reference voltage. This reference changes with the ILED setting. The internal error amplifier (EA) regulates the average minimum 

VLEDx to the internal reference voltage. The EA’s output is connected to the external current-loop compensation network on the COMP1 pin through an inner switch (S1). During the PWM on time, S1 is on and the minimum VLEDx is regulated by this control loop. The flyback power is set by the COMP1 voltage (VCOMP1). During the PWM off period, S1 is turned off, the compensation network is disconnected from the EA’s output, and VCOMP1 remains steady until the next PWM on interval. The EA’s output is also pulled low during the PWM off period. 

## _**Output Voltage Regulation when PWM**_ 

## _**Dimming Is Off**_ 

When PWM dimming is off, the output voltage (VOUT) is fed back to the FB pin and the internal VREF is equal to 1.2V. During the PWM off period, the MP4658 regulates VOUT by controlling the flyback power stage. The internal voltage-loop EA regulates the average VFB to its internal reference. The EA’s output is connected to the external voltage-loop compensation network on the COMP2 pin. The flyback power is set by the COMP2 voltage (VCOMP2). 

When PWM dimming is on, the flyback power is controlled by VCOMP1 and VOUT varies with different dimming conditions. The voltage-loop EA’s output is also pulled low. 

## **Dimming Control** 

The MP4658 provides analog dimming and PWM dimming for ILED through the separate ADIM and PDIM pin. For analog dimming, apply a pulse signal with a frequency above 5kHz to the ADIM pin and pull the PDIM pin high. The pulse signal’s duty cycle sets the ILED amplitude. For PWM dimming, the duty cycle of input signal at the ADIM pin sets the peak ILED value. ILED is chopped by the input PWM signal at the PDIM pin. The brightness of the LED string is proportional to the external PWM signal’s duty cycle, which helps achieve fast and highcontrast ratio PWM dimming. For analog PWM dimming, apply a <5kHz pulse signal to the ADIM pin and pull the PDIM pin high. The ADIM pin’s input impedance determines the internal analog dimming RC filter and the rising/falling speed during PWM dimming. If the input 

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impedance on ADIM is below 15kΩ, then the RC filter constant is smaller and the ILED rising/falling speed during PWM dimming is faster. Soft PWM dimming for ILED helps reduce the audible noise. 

## **Protection Features** 

The MP4658 integrates sufficient protections for the output voltage stage and LED driver stage. The protections for the VOUT stage includes system over-voltage protection (OVP) and open feedback loop protection. Fault protections for the LED driver stage include open LED protection, short LED string protection, one or more LED short protection and LEDx short to ground protection. 

## **Output Over-Voltage Protection (OVP)** 

The FB pin senses VOUT for regulation and OVP. If VFB is 24% greater than VREF, the MP4658 triggers output OVP and the OPT pin is clamped to 3.3V when the LED stage is off. Output OVP is disabled when the LED stage is on. The fault indicator outputs a low voltage when output OVP is triggered. 

## **Feedback Open Protection** 

If VFB is below 500mV, the IC latches off and the fault indicator outputs a low voltage. 

## **Open LED Protection** 

The LED string voltage is sensed by the OVP pin. Open LED protection is achieved via the OVP pin voltage and the LEDx (LED1~4) pin voltage detections. If one or more LED strings are open, the respective VLEDx is pulled to ground and the LED string’s output voltage keeps increasing until the OVP pin’s voltage (VOVP) reaches the OVP threshold. When VOVP reaches 2.4V and VLEDx is below 100mV, the MP4658 triggers open LED protection. The IC marks off the open string(s), meaning any that have a VLEDx below 100mV. The remaining LED strings discharge the output voltage and VOVP decreases until it falls below the OVP threshold. Then the LED control loop recovers and the minimum VLEDx of the remaining LED strings is regulated. If an LED open fault is triggered, the fault indicator pin outputs a low voltage. 

If all LED strings are open, all strings are marked off and the LED control loop is disabled. If an open all LED strings condition occurs, the IC operation mode switches from constant current (CC) mode to constant voltage (CV) mode. 

If VOVP exceeds 3V, the IC latches off. This function protects the components from any out of control condition (such as the LED output voltage exceeding VOV_LED when the OPT pin is not pulled high) and keeps the system safe. 

## **LED Short Protection** 

VLEDx is used to indicate a short LED condition. If an LED string is shorted, the respective VLEDx increases significantly. If VLEDx exceeds 5V for 5ms, a short fault is triggered, and the MP4658 marks off this string. Other strings keep working if they are not experiencing a short. 

If short protection is triggered, the fault indicator outputs a low voltage. 

## **LEDx Short-to-Ground Protection** 

If COMP1 is saturated and VLEDx is low for 30ms, the IC triggers LEDx short-to-ground protection. The LED control loop is disabled, and the output voltage is regulated in constant voltage (CV) mode. If this protection is triggered, the fault indicator outputs a low voltage. 

The LED loop can recover from a fault condition by toggling the ADIM or PDIM pin. Pull either pin low for more than 30ms, then pull it high. The fault condition should be removed, and the fault indicator should reset. 

## **Thermal Protection** 

Thermal protection is integrated in the MP4658. If the die temperature exceeds the overtemperature (OT) threshold (150°C), the IC stops working until the die temperature falls to 125°C. 

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## **APPLICATION INFORMATION** 

## **Open LED Protection (OVP)** 

The OVP pin monitors the LED output voltage and controls open LED protection. Connect this pin to the LED output voltage through a voltage divider, and set the OVP point using Equation (1): 

**==> picture [185 x 26] intentionally omitted <==**

Where ROVPH and ROVPL are the high-side and low-side resistors of the voltage divider, respectively. 

## **Output Voltage Feedback (FB)** 

The FB pin feeds back the output voltage (VOUT). Connect this pin to the output voltage through a voltage divider. This voltage divider determines VOUT, which can be calculated with Equation (2): 

**==> picture [183 x 28] intentionally omitted <==**

Where RVFBH and RVFBL are the high-side and low-side resistors of the voltage divider, respectively. 

## **LED Current Setting** 

The LED current (ILED) is set by the resistor on the ISET pin. The ISET pin outputs a 1.6V voltage and its sourcing current determines ILED. Estimate ILED with Equation (3): 

**==> picture [201 x 27] intentionally omitted <==**

## **Selecting the Turn Ratios of the Power Transformer** 

The power transformer includes three power windings: the primary-side winding, the LED secondary-side winding and the output voltage winding. Follow these steps to design the turn ratios of the power transformer: 

Design the turn ratio between the primary-side winding and LED secondary-side winding using NP:NLED. The maximum voltage stress on the primary-side switch occurs at the maximum input AC voltage and maximum output LED voltage. 

Calculate the maximum voltage stress on the primary-side switch (VDS_PRI) with Equation (4): 

**==> picture [225 x 25] intentionally omitted <==**

Considering the leakage inductance of the flyback transformer, assume a 60V spike voltage on the primary-side switch and a 10% derating of the switch voltage capability. Calculate the primary-side switch’s rating voltage with Equation (5): 

**==> picture [183 x 13] intentionally omitted <==**

Calculate the turn ratio (NP:NLED) between the primary-side winding (NP) and the secondary LED winding (NLED) with Equation (6): 

**==> picture [241 x 98] intentionally omitted <==**

Design the turn ratio between the LED winding and the output voltage winding: NLED:NSYS. When the LED stage is working, the LED winding voltage (VLED) clamps the system winding voltage via the turn ratio. Ensure that VOUT exceeds the voltage set with Equation (2) when the LED stage is on with the minimum VLED. Estimate this relationship with Equation (7): 

**==> picture [185 x 37] intentionally omitted <==**

Where VLED_MIN is the minimum LED output voltage. Choose a 10% margin for production design, calculated with Equation (8): 

**==> picture [198 x 28] intentionally omitted <==**

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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK** 

## **PCB Layout Guidelines** 

Efficient PCB layout is important to achieve reliable operation, good EMI performance and excellent thermal performance. For the best results, refer to Figure 4 and follow the guidelines below: 

1. Minimize the area of the power stage loop. This includes the primary loop (input capacitor, transformer, and MOSFET sense resistor), as well as the secondary-side winding loop (transformer, rectifier, and output capacitor). 

2. Separate the output loop GND and control circuit GND, and only connect them at the GND pin. 

**==> picture [172 x 135] intentionally omitted <==**

**----- Start of picture text -----**<br>
D1<br>PDIM 1 16 FF<br>R5 C1<br>OPT 2 15 VIN<br>R1<br>FB 3 14 NC<br>R2<br>COMP2 4 13 ADIMP<br>C4 C5<br>R4<br>COMP1 5 12 ISET<br>C3 R3<br>C2 OVP 6 11 LED3<br>LED1 7 10 LED4<br>LED2 8 9 GND<br>**----- End of picture text -----**<br>


**Figure 4: Recommended PCB Layout** 

3. Place the peripheral electronic components (such as those for VIN, FB, COMP1, and COMP2) as close to the IC as possible to decouple noise. 

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## **TYPICAL APPLICATION CIRCUIT** 

**==> picture [355 x 208] intentionally omitted <==**

**----- Start of picture text -----**<br>
TM D1 VLED<br>Flyback<br>° C1 R1 I<br>85V to 265VAC 380V Bus100V to  NP NLED R2<br>M1 _} NSYS D2 ~ C2 VOUT DC/DC C3 VSYS ° ; Vv<br>1 R3<br>] R4<br>C4<br>t + 15 VIN FB 3 => R5<br>C5 R6 4 COMP2 LED1 7<br>_ controllerFlyback  Hs< H C6 F— R7 5 COMP1 MP4658 LED2 8<br>{¢+— R8 o 12 ISET OVP 6<br>R9 2 OPT GND 9<br>16 FF NC 14<br>>5kHz<br>ADIM 13 ADIM LED3 11<br>| >100Hz PDIM 1 PDIM LED4 10<br>**----- End of picture text -----**<br>


**Figure 5: MP4658 Typical Application Circuit (Flyback 4-String LED Driver)** 

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## **PACKAGE INFORMATION** 

## **SOIC-16** 

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## **CARRIER INFORMATION** 

**==> picture [485 x 167] intentionally omitted <==**

**----- Start of picture text -----**<br>
|||||||||
|---|---|---|---|---|---|---|---|
|0000000|
|Pin1|1|1|1|1|
|a \|rrr|
|Feed Direction|
|Package|Quantity/|Quantity/|Quantity/|Reel|Carrier|Carrier|
|Part Number|
|Description|Reel|Tube|Tray|Diameter|Tape Width|Tape Pitch|
|MP4658GS-Z|SOIC-16|2500|50|N/A|13in|16mm|8mm|

**----- End of picture text -----**<br>


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**MP4658 – 4-STRING, 80V RETURN LED DRIVER WITH AC/DC FEEDBACK REVISION HISTORY Revision # Revision Date Description Pages Updated** 1.0 10/13/2021 Initial Release - ~~pp~~[MPS] 

**Notice:** The information in this document is subject to change without notice. Please contact MPS for current specifications. Users should warrant and guarantee that third-party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. 

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