FDMS3669S

## **FDMS3669S** 

## **PowerTrench[®] Power Stage** 

## **General Description** 

## **Asymmetric Dual N-Channel MOSFET Features** 

This device includes two specialized N-Channel MOSFETs in a dual PQFN package. The switch node has been internally connected to enable easy placement and routing of synchronous buck converters. The control MOSFET (Q1) and synchronous SyncFET[TM] (Q2) have been designed to provide optimal power efficiency. 

Q1: N-Channel 

Max rDS(on) = 10 mΩ at VGS = 10 V, ID = 13 A 

Max rDS(on) = 14.5 mΩ at VGS = 4.5 V, ID = 10 A 

Q2: N-Channel 

Max rDS(on) = 5 mΩ at VGS = 10 V, ID = 18 A 

## **Applications** 

Max rDS(on) = 5.2 mΩ at VGS = 4.5 V, ID = 17 A 

Computing Communications General Purpose Point of Load 

Low inductance packaging shortens rise/fall times, resulting in lower switching losses 

MOSFET integration enables optimum layout for lower circuit inductance and reduced switch node Notebook VCORE ringing 

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RoHS Compliant<br>Pin 1 G1<br>D1<br>Pin 1 D1 D1 D1 S2 5 Q2 4 D1<br>PHAS S2 6 PHAS 3 D1<br>E(S1/ E<br>G2 D2) S2 7 2 D1<br>S2<br>os S2 G2 8 Q1 1 G1<br>S2<br>Top Power 56 Bottom<br>MOSFET Maximum Ratings TA = 25 °C unless otherwise noted<br>Symbol Parameter Q1 Q2 Units<br>VDS Drain to Source Voltage 30 30 V<br>VGS Gate to Source Voltage  (Note 3) ±20 ±12 V<br>Drain Current      -Continuous  (Package limited)    TC = 25 °C 24 60<br>ID -Continuous  -Continuous (Silicon limited)     T   TCA = 25 °C= 25 °C 1343 [1a] 1875 [1b] A<br>-Pulsed (Note 6) 50 60<br>EAS Single Pulse Avalanche Energy 61 [4] 48 [5] mJ<br>PD Power DissiPower Dissippation for Sination for Singgle Ole Opperation  eration     T  TA A = 25 °C= 25 °C 2.21.0 [1a][1c] 2.51.0 [1b][1d] W<br>i TJ, TSTG Operating and Storage Junction Temperature Range -55 to +150 °C<br>Thermal Characteristics<br>RθJA Thermal Resistance, Junction to Ambient          57 [1a] 50 [1b]<br>RθJA Thermal Resistance, Junction to Ambient          125 [1c] 120 [1d] °C/W<br>—a RθJC Thermal Resistance, Junction to Case     5.0 2.8<br>Package Marking and Ordering Information<br>Device Marking Device Package Reel Size Tape Width Quantity<br>9ACF<br>FDMS3669S Power 56 13 ” 12 mm 3000 units<br>21CD<br>Se<br>ee ee a<br>**----- End of picture text -----**<br>


©2013 Semiconductor Components Industries,LLC August-2017,Rev.3 

Publication Order Number: FDMS3669S/D 

## **Electrical Characteristics** TJ = 25 °C unless otherwise noted 

|**Electrica**|**l Characteristics**TJ= 25 °C u|nless otherwise noted||||||||
|---|---|---|---|---|---|---|---|---|---|
|**Symbol**|**Parameter**|**Test Conditions**|**Type**|**Min**||**Typ**|**Max**||**Units**|
|**Off Characteristics**||||||||||
|BVDSS|Drain to Source Breakdown Voltage|ID= 250μA, VGS= 0 V<br>ID= 1 mA, VGS= 0 V|Q1<br>Q2|30<br>30|||||V|
|ΔBVDSS<br>ΔTJ|Breakdown Voltage Temperature<br>Coefficient|ID= 250μA, referenced to 25 °C<br>ID= 10 mA, referenced to 25 °C|Q1<br>Q2|||16<br>20|||mV/°C|
|IDSS|Zero Gate Voltage Drain Current|VDS= 24 V, VGS= 0 V|Q1<br>Q2||||1<br>500||μA<br>μA|
|IGSS|Gate to Source Leakage Current|VGS= 20 V, VDS= 0 V<br>VGS= 12 V, VDS= 0 V|Q1<br>Q2||||100<br>100||nA<br>nA|
|**On Characteristics**||||||||||
|VGS(th)|Gate to Source Threshold Voltage|VGS= VDS,  ID= 250μA<br>VGS= VDS,  ID= 1 mA|Q1<br>Q2|1.1<br>1.1||2.0<br>1.5|2.7<br>2.5||V|
|ΔVGS(th)<br>ΔTJ|Gate to Source Threshold Voltage<br>Temperature Coefficient|ID= 250μA, referenced to 25 °C<br>ID= 10 mA, referenced to 25 °C|Q1<br>Q2|||-6<br>-3|||mV/°C|
|rDS(on)|Drain to Source On Resistance|VGS= 10 V,  ID= 13 A<br>VGS= 4.5 V,  ID= 10 A<br>VGS= 10 V,  ID= 13 A , TJ= 125 °C|Q1|||8.1<br>12<br>11|10<br>14.5<br>14.5||mΩ|
|||VGS= 10 V,  ID= 18 A<br>VGS= 4.5 V,  ID= 17 A<br>VGS= 10 V,  ID= 18 A , TJ= 125 °C|Q2|||2.8<br>3.5<br>4.0|5.0<br>5.2<br>7.1|||
|gFS|Forward Transconductance|VDS= 5 V,  ID= 13 A<br>VDS= 5 V,  ID= 18 A|Q1<br>Q2|||53<br>113|||S|
|**Dynamic Characteristics**||||||||||
|Ciss|Input Capacitance|Q1:<br>VDS= 15 V, VGS= 0 V, f = 1 MHZ<br>Q2:<br>VDS= 15 V, VGS= 0 V, f = 1 MHZ|Q1<br>Q2|||1205<br>1469|1605<br>2060||pF|
|Coss|Output Capacitance||Q1<br>Q2|||370<br>485|495<br>680||pF|
|Crss|Reverse Transfer Capacitance||Q1<br>Q2|||35<br>59|55<br>90||pF|
|Rg|Gate Resistance||Q1<br>Q2|0.3<br>0.2||1.6<br>1.4|3.2<br>3.0||Ω|
|**Switching Characteristics**||||||||||
|td(on)|Turn-On Delay Time|Q1:<br>VDD= 15 V, ID= 13 A,  RGEN= 6Ω<br>Q2:<br>VDD= 15 V, ID= 18 A,  RGEN= 6Ω|Q1<br>Q2|||9<br>7||18<br>14|ns|
|tr|Rise Time||Q1<br>Q2|||3<br>3||10<br>10|ns|
|td(off)|Turn-Off Delay Time||Q1<br>Q2|||20<br>24||36<br>40|ns|
|tf|Fall Time||Q1<br>Q2|||3<br>3||10<br>10|ns|
|Qg|Total Gate Charge|VGS= 0 V to 10 V|Q1<br>Q2|||17<br>24||24<br>34|nC|
|Qg|Total Gate Charge|VGS= 0 V to 4.5 V|Q1<br>Q2|||7.5<br>12||12<br>17|nC|
|Qgs|Gate to Source Gate Charge||Q1<br>Q2|||3.9<br>3.3|||nC|
|Qgd|Gate to Drain “Miller” Charge||Q1<br>Q2|||2.0<br>3.6|||nC|



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|VSD|Source to Drain Diode  Forward Voltage|VGS= 0 V, IS= 13 A           (Note 2)<br>VGS= 0 V, IS= 2 A<br>(Note 2)<br>VGS= 0 V, IS= 18 A           (Note 2)<br>VGS = 0 V, IS = 2 A<br> (Note 2)|Q1<br>Q1<br>Q2<br>Q2||0.8<br>0.7<br>0.8<br>0.7|1.2<br>1.2<br>1.2<br>1.2|V|
|---|---|---|---|---|---|---|---|
|trr|Reverse Recovery Time|Q1:<br>IF= 13 A, di/dt = 100 A/μs<br>Q2:<br>IF= 18 A, di/dt = 300 A/μs|Q1<br>Q2||24<br>21|38<br>33|ns|
|Qrr|Reverse Recovery Charge||Q1<br>Q2||8<br>16|15<br>31|nC|



Notes: 

1. RθJA is determined with the device mounted on a 1 in[2] pad 2 oz copper pad on a 1.5 x 1.5 in. board of FR-4 material. RθJC is guaranteed by design while RθCA is determined by the user's board design. 

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b. 50 °C/W when mounted on<br>a. 57 °C/W when mounted on  a 1 in [2 ] pad of  2 oz  copper<br> a 1 in [2 ] pad of  2 oz  copper<br>c. 125 °C/W when mounted on  a d. 120 °C/W when mounted on  a<br>minimum pad of 2 oz copper minimum pad of 2 oz copper<br>00000<br>G DF DS SF SS G DF DS SF SS<br>G DF DS SF SS<br>G DF DS SF SS<br>**----- End of picture text -----**<br>


2. Pulse Test: Pulse Width < 300 μs, Duty cycle < 2.0%. 

3. As an N-ch device, the negative Vgs rating is for low duty cycle pulse ocurrence only. No continuous rating is implied with the negative Vgs rating. 

4. EAS of 61 mJ is based on starting TJ = 25[o] C; N-ch: L = 3 mH, IAS = 6.4 A, VDD = 30 V, VGS = 10 V. 100% test at L= 0.1 mH, IAS = 20 A. 

5. EAS of 48 mJ is based on starting TJ = 25[o] C; N-ch: L = 3 mH, IAS = 5.7 A, VDD = 30 V, VGS = 10 V. 100% test at L= 0.1 mH, IAS = 17 A. 

6. Pulsed Id limited by junction temperature,td<=10uS. Please refer to SOA curve for more details. 

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## **Typical Characteristics (Q1 N-Channel)** TJ = 25 °C unless otherwise noted 

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50 5<br>VGSVGS = 6 V = 10 V VGS = 3.5 V VGS = 4 V<br>40 4<br>VGS = 4.5 V<br>VGS = 4 V<br>30 3<br>20 2 VGS = 6 V VGS = 4.5 V<br>10 V GS  = 3.5 V 1<br>PULSE DURATION = 80  μ s PULSE DURATION = 80  μ s VGS =  10 V<br>DUTY CYCLE = 0.5% MAX DUTY CYCLE = 0.5% MAX<br>0 0<br>0.0 0.5 1.0 1.5 2.0 2.5 0 10 20 30 40 50<br>VDS, DRAIN TO SOURCE VOLTAGE (V) ID, DRAIN CURRENT (A)<br>NORMALIZED<br>, DRAIN CURRENT (A)<br>ID<br>DRAIN TO SOURCE ON-RESISTANCE<br>**----- End of picture text -----**<br>


## **Figure 1.  On Region Characteristics** 

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1.6<br>ID = 13 A<br>VGS = 10 V<br>1.4<br>1.2<br>1.0<br>0.8<br>0.6<br>-75 -50 -25 0 25 50 75 100 125 150<br>TJ, JUNCTION TEMPERATURE ( [o] C)<br>Figure 3.  Normalized  On  Resistance<br>vs Junction Temperature<br>50<br>PULSE DURATION = 80  μ s<br>DUTY CYCLE = 0.5% MAX<br>40<br>VDS = 5 V<br>30<br>TJ = 150  [o] C<br>20<br>TJ = 25  [o] C<br>10<br>TJ = -55  [o] C<br>0<br>1 2 3 4 5<br>VGS, GATE TO SOURCE VOLTAGE (V)<br>Figure 5.  Transfer Characteristics<br>NORMALIZED<br> DRAIN TO SOURCE ON-RESISTANCE<br>, DRAIN CURRENT (A)<br>ID<br>**----- End of picture text -----**<br>


**Figure 2.      Normalized On-Resistance vs Drain Current and Gate Voltage** 

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30<br>ID = 13 A PULSE DURATION = 80 DUTY CYCLE = 0.5% MAX μ s<br>25<br>20<br>TJ = 125  [o] C<br>15<br>10<br>TJ = 25  [o] C<br>5<br>2 4 6 8 10<br>VGS, GATE TO SOURCE VOLTAGE (V)<br>Figure 4.   On-Resistance vs  Gate to<br>Source Voltage<br>50<br>V GS  = 0 V<br>10<br>TJ = 150  [o] C<br>TJ = 25 [ o] C<br>1<br>TJ = -55  [o] C<br>0.1<br>0.0 0.2 0.4 0.6 0.8 1.0 1.2<br>VSD, BODY DIODE FORWARD VOLTAGE (V)<br>) Ω<br>(m<br>DRAIN TO<br>rDS(on),<br>SOURCE ON-RESISTANCE<br>, REVERSE DRAIN CURRENT (A)<br>IS<br>**----- End of picture text -----**<br>


**Figure 6.    Source to Drain  Diode Forward Voltage vs Source Current** 

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**Typical Characteristics (Q1 N-Channel)** TJ = 25 °C unless otherwise noted 

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10 2000<br>ID = 13 A 1000 Ciss<br>8<br>VDD = 10 V<br>6 Coss<br>VDD =15 V VDD = 20 V<br>100<br>4<br>2 f = 1 MHz Crss<br>VGS = 0 V<br>0 10<br>0 3 6 9 12 15 18 0.1 1 10 30<br>Qg, GATE CHARGE (nC) VDS, DRAIN TO SOURCE VOLTAGE (V)<br>Figure 7.  Gate Charge Characteristics Figure 8.      Capacitance vs Drain<br>to Source Voltage<br>25 50<br>20 40<br>VGS = 10 V<br>TJ = 25 [ o] C<br>15 30<br>TJ = 125  [o] C TJ = 100 [ o] C 20 VGS = 4.5 V<br>10<br>Limited by Package<br>10<br>5<br>R θ JC = 5.0  [o] C/W<br>1 0<br>0.01 0.1 1 10 40 25 50 75 100 125 150<br>tAV, TIME IN AVALANCHE (ms) TC, CASE TEMPERATURE (oC)<br>Figure 9.  Unclamped Inductive     Figure 10.  Maximum Continuous Drain<br>Switching Capability Current vs Case Temperature<br>100 1000<br>SINGLE PULSE<br>100  μ s R θ JA  = 125 [ o] C/W<br>10 100<br>1 ms<br>1 THIS AREA IS  10<br>LIMITED BY rDS(on) 10 ms<br>100 ms<br>SINGLE PULSE<br>0.1 TJ = MAX RATED 1 s 1<br>R θ JA = 125  [o] C/W 10 sDC<br>TA = 25  [o] C<br>0.010.01 0.1 1 10 100200 0.110-4 10-3 10-2 10-1 1 10 100 1000<br>VDS, DRAIN to SOURCE VOLTAGE (V) t, PULSE WIDTH (sec)<br>Figure 11.  Forward Bias Safe     Figure 12.  Single Pulse Maximum<br>Operating Area  Power Dissipation<br>CAPACITANCE (pF)<br>, GATE TO SOURCE VOLTAGE (V)<br>GS<br>V<br>DRAIN CURRENT (A)<br>,<br>ID<br>, AVALANCHE CURRENT (A)<br>IAS<br>, DRAIN CURRENT (A)<br>ID<br>, PEAK TRANSIENT POWER (W)P)(PK<br>**----- End of picture text -----**<br>


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Typical Characteristics (Q1 N-Channel)  TJ = 25 °C unless otherwise noted<br>**----- End of picture text -----**<br>


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2<br>DUTY CYCLE-DESCENDING ORDER<br>1<br>D = 0.5<br>0.1   0.2   0.1 PDM<br>  0.05<br>  0.02<br>  0.01 t 1<br>0.01 SINGLE PULSE t 2<br>NOTES:<br>R θ JA  = 125  [o] C/W DUTY FACTOR: D = t1/t2<br>(Note 1c)  PEAK T J  = P DM  x Z θJA  x R θJA  + T A<br>0.00110-4 10-3 10-2 10-1 1 10 100 1000<br>t, RECTANGULAR PULSE DURATION (sec)<br>Figure 13.  Junction-to-Ambient Transient Thermal Response Curve<br>Z JA θ<br>IMPEDANCE,<br>NORMALIZED THERMAL<br>**----- End of picture text -----**<br>


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## **Typical Characteristics (Q2 N-Channel)** TJ =  25[o] C unlenss otherwise noted 

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60 8<br>VGS = 10 V PULSE DURATION = 80  μ s<br>V GS = 4.5 V VGS = 2.5 V DUTY CYCLE = 0.5% MAX<br>45 VGS = 3.5 V 6<br>30 VGS = 3 V 4<br>VGS = 2.5 V VGS = 3.5 V<br>15 2 VGS = 3 V<br>PULSE DURATION = 80  μ s<br>DUTY CYCLE = 0.5% MAX VGS = 4.5 V VGS = 10 V<br>0 0<br>0.0 0.3 0.6 0.9 1.2 1.5 0 15 30 45 60<br>VDS, DRAIN TO SOURCE VOLTAGE (V) ID, DRAIN CURRENT (A)<br>Figure 14. On-Region Characteristics Figure 15. Normalized on-Resistance vs Drain<br>Current and Gate  Voltage<br>1.6 20<br>ID = 18 A PULSE DURATION = 80  μ s<br>VGS = 10 V DUTY CYCLE = 0.5% MAX<br>1.4<br>15<br>ID = 18 A<br>1.2<br>10<br>1.0<br>TJ = 125 [ o] C<br>5<br>0.8<br>TJ = 25  [o] C<br>0.6 0<br>-75 -50 -25 0 25 50 75 100 125 150 2 4 6 8 10<br>TJ, JUNCTION TEMPERATURE ( [o] C) VGS, GATE TO SOURCE VOLTAGE (V)<br>Figure 16. Normalized On-Resistance  Figure 17. On-Resistance vs Gate to<br>vs Junction Temperature Source Voltage<br>60 100<br>PULSE DURATION = 80  μ s VGS = 0 V<br>DUTY CYCLE = 0.5% MAX<br>10<br>45<br>VDS = 5 V TJ = 125  [o] C<br>TJ = 125  [o] C 1<br>30<br>TJ = 25  [o] C 0.1 TJ = 25 [ o] C<br>15 0.01 T J  = -55  [o] C<br>TJ = -55  [o] C<br>0 1E-3<br>1.0 1.5 2.0 2.5 3.0 0.0 0.2 0.4 0.6 0.8 1.0<br>VGS, GATE TO SOURCE VOLTAGE (V) VSD, BODY DIODE FORWARD VOLTAGE (V)<br>Figure 18. Transfer Characteristics Figure 19. Source to Drain Diode<br>NORMALIZED<br>, DRAIN CURRENT (A)<br>ID<br>DRAIN TO SOURCE ON-RESISTANCE<br>) Ω<br>(m<br>DRAIN TO<br>NORMALIZED rDS(on),<br>SOURCE ON-RESISTANCE<br> DRAIN TO SOURCE ON-RESISTANCE<br>, DRAIN CURRENT (A)<br>ID<br>, REVERSE DRAIN CURRENT (A)<br>IS<br>**----- End of picture text -----**<br>


**Figure 19. Source to Drain Diode Forward Voltage vs Source Current** 

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**Typical Characteristics (Q2 N-Channel)** TJ = 25[o] C unless otherwise noted 

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10 10000<br>ID = 17 A<br>8 Ciss<br>VDD = 10 V 1000<br>6<br>VDD = 15 V<br>C oss<br>4<br>VDD = 20 V 100<br>2 f = 1 MHz<br>V GS  = 0 V C rss<br>0 10<br>0 10 20 30 0.1 1 10 30<br>Qg, GATE CHARGE (nC) VDS, DRAIN TO SOURCE VOLTAGE (V)<br>Figure 20. Gate Charge Characteristics Figure 21. Capacitance vs Drain<br>to Source Voltage<br>100 80<br>60<br>VGS = 10 V<br>TJ = 100 [ o] C VGS = 4.5 V<br>10 40<br>Limited by Package<br>T J  = 125  [o] C TJ = 25 [ o] C 20 R θ JC = 2.8  [o] C/W<br>1 0<br>1E-3 0.01 0.1 1 10 100 25 50 75 100 125 150<br>tAV, TIME IN AVALANCHE (ms) TC, CASE TEMPERATURE (oC)<br>Figure 22. Unclamped Inductive     Figure 23. Maximun Continuous Drain<br>Switching Capability Current vs Case Temperature<br>100 2000<br>1000<br>100  μ s SINGLE PULSE<br>10 R θ JA  = 120 [ o] C/W<br>100<br>1 THIS AREA IS  1 ms<br>LIMITED BY rDS(on) 100 ms10 ms 10<br>SINGLE PULSE 1s<br>0.1 TJ = MAX RATED 10s<br>R θ JA = 120  [o] C/W CURVE BENT ON<br>T A = 25  [o] C MEASURED DATA DC 1<br>0.010.01 0.1 1 10 100200 0.510-4 10-3 10-2 10-1 100 101 100 1000<br>VDS, DRAIN to SOURCE VOLTAGE (V) t, PULSE WIDTH (sec)<br>Figure 24.  Forward Bias Safe     Figure 25. Single  Pulse Maximum<br>Operating Area Power Dissipation<br>CAPACITANCE (pF)<br>, GATE TO SOURCE VOLTAGE (V)<br>GS<br>V<br>DRAIN CURRENT (A)<br>,<br>ID<br>, AVALANCHE CURRENT (A)<br>IAS<br>, DRAIN CURRENT (A)<br>ID<br>, PEAK TRANSIENT POWER (W)P)(PK<br>**----- End of picture text -----**<br>


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Typical Characteristics (Q2 N-Channel) TJ = 25  [o] C unless otherwise noted<br>2<br>DUTY CYCLE-DESCENDING ORDER<br>1<br>D = 0.5<br>0.2<br>0.1<br>   0.1<br>   0.05<br>   0.02 PDM<br>   0.01<br>0.01<br>t1<br>SINGLE PULSE<br>t 2<br>1E-3 (Note 1d)  R θ JA = 120  [o] C/W NOTES: DUTY FACTOR: D = t1/t2<br>PEAK TJ = PDM x Z θJA  x R θJA  + TA<br>1E-410-4 10-3 10-2 10-1 100 101 100 1000<br>t, RECTANGULAR PULSE DURATION (sec)<br>Z JA θ<br>IMPEDANCE,<br>NORMALIZED THERMAL<br>**----- End of picture text -----**<br>


**Figure 26.  Junction-to-Ambient Transient Thermal Response Curve** 

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## **Typical Characteristics** (continued) 

## **SyncFET[TM] Schottky body diode Characteristics** 

ON Semiconductor’s SyncFET[TM] process embeds a Schottky diode in parallel with PowerTrench MOSFET. This diode exhibits similar characteristics to a discrete external Schottky diode in parallel with a MOSFET. Figure 27 shows the reverse recovery characteristic of the FDMS3669S. 

Schottky barrier diodes exhibit significant leakage at high temperature and high reverse voltage. This will increase the power in the device. 

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20 10-2<br>15 10-3 TJ = 125  [o] C<br>didt = 300 A/ μ s<br>10<br>10-4 TJ = 100  [o] C<br>5<br>10-5<br>0 TJ = 25  [o] C<br>-5 10-6<br>-40 0 40 80 120 160 0 5 10 15 20 25 30<br>TIME (ns) VDS, REVERSE VOLTAGE (V)<br>CURRENT (A)<br>, REVERSE LEAKAGE CURRENT (A)<br>IDSS<br>**----- End of picture text -----**<br>


**Figure 27. FDMS3669S SyncFET[TM] body diode reverse recovery characteristic** 

**Figure 28. SyncFET[TM] body diode reverse leakage  versus drain-source voltage** 

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## **Application Information** 

## **1. Switch Node Ringing Suppression** 

ON Semiductor’s Power Stage products incorporate a proprietary design* that minimizes the peak overshoot, ringing voltage on the switch node (PHASE) without the need of any external snubbing components in a buck converter. As shown in the figure 29, the Power Stage solution rings significantly less than competitor solutions under the same set of test conditions. 

> 1||I }ty | lI | | [ !| Chl Sov M20.0neS0G54 IT 8.0nehx M20.Onr 5.005% IT B.Opetat AChi + SOY AChI5.0" **Power Stage Device Competitors solution** 

**Figure 29.   Power Stage phase node rising edge, High Side Turn on** 

*Patent Pending 

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**Figure 30.  Shows the Power Stage in a buck converter topology** 

## **2. Recommended PCB Layout Guidelines** 

As a PCB designer, it is necessary to address critical issues in layout to minimize losses and optimize the performance of the power train. Power Stage is a high power density solution and all high current flow paths, such as VIN (D1), PHASE (S1/D2) and GND (S2), should be short and wide for better and stable current flow, heat radiation and system performance. A recommended layout procedure is discussed below to maximize the electrical and thermal performance of the part. 

**Figure 31.  Recommended PCB Layout** 

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## **Following is a guideline, not a requirement which the PCB designer should consider:** 

1. Input ceramic bypass capacitors C1 and C2 must be placed close to the D1 and S2 pins of Power Stage to help reduce parasitic inductance and high frequency conduction loss induced by switching operation. C1 and C2 show the bypass capacitors placed close to the part between D1 and S2.  Input capacitors should be connected in parallel close to the part. Multiple input caps can be connected depending upon the application. 

2. The PHASE copper trace serves two purposes; In addition to being the current path from the Power Stage package to the output inductor (L), it also serves as heat sink for the lower FET in the Power Stage package. The trace should be short and wide enough to present a low resistance path for the high current flow between the Power Stage and the inductor. This is done to minimize conduction losses and limit temperature rise. Please note that the PHASE node is a high voltage and high frequency switching node with high noise potential. Care should be taken to minimize coupling to adjacent traces. The reference layout in figure 31 shows a good balance between the thermal and electrical performance of Power Stage. 

3. Output inductor location should be as close as possible to the Power Stage device for lower power loss due to copper trace resistance. A shorter and wider PHASE trace to the inductor reduces the conduction loss. Preferably the Power Stage should be directly in line (as shown in figure 31) with the inductor for space savings and compactness. 

4. The PowerTrench[®] Technology MOSFETs used in the Power Stage are effective at minimizing phase node ringing. It allows the part to operate well within the breakdown voltage limits. This eliminates the need to have an external snubber circuit in most cases. If the designer chooses to use an RC snubber, it should be placed close to the part between the PHASE pad and S2 pins to dampen the high-frequency ringing. 

5. The driver IC should be placed close to the Power Stage part with the shortest possible paths for the High Side gate and Low Side gates through a wide trace connection. This eliminates the effect of parasitic inductance and resistance between the driver and the MOSFET and turns the devices on and off as efficiently as possible. At higher-frequency operation this impedance can limit the gate current trying to charge the MOSFET input capacitance. This will result in slower rise and fall times and additional switching losses. Power Stage has both the gate pins on the same side of the package which allows for back mounting of the driver IC to the board. This provides a very compact path for the drive signals and improves efficiency of the part. 

6. S2 pins should be connected to the GND plane with multiple vias for a low impedance grounding. Poor grounding can create a noise transient offset voltage level between S2 and driver ground. This could lead to faulty operation of the gate driver and MOSFET. 

7. Use multiple vias on each copper area to interconnect top, inner and bottom layers to help smooth current flow and heat conduction. Vias should be relatively large, around 8 mils to 10 mils, and of reasonable inductance. Critical high frequency components such as ceramic bypass caps should be located close to the part and on the same side of the PCB. If not feasible, they should be connected from the backside via a network of low inductance vias. 

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