PD - 94579C IRF7821 HEXFET(R) Power MOSFET Applications l High Frequency Point-of-Load Synchronous Buck Converter for Applications in Networking & Computing Systems. Benefits l Very Low RDS(on) at 4.5V VGS l Low Gate Charge l Fully Characterized Avalanche Voltage and Current VDSS RDS(on) max Qg(typ.) 30V 9.1mW@VGS= 10V 9.3nC A A D S 1 8 S 2 7 D S 3 6 D G 4 5 D SO-8 Top View Absolute Maximum Ratings Parameter Max. Units 30 V VDS Drain-to-Source Voltage VGS Gate-to-Source Voltage Continuous Drain Current, VGS @ 10V 13.6 IDM Continuous Drain Current, VGS @ 10V Pulsed Drain Current 100 PD @TA = 25C Power Dissipation 2.5 PD @TA = 70C Power Dissipation TJ Linear Derating Factor Operating Junction and TSTG Storage Temperature Range ID @ TA = 25C ID @ TA = 70C f f 20 A 11 c W 1.6 0.02 -55 to + 155 W/C C Thermal Resistance Parameter RJL RJA g fg Junction-to-Ambient Junction-to-Drain Lead Notes through Typ. Max. Units --- 20 C/W --- 50 are on page 10 www.irf.com 1 05/23/07 http://store.iiic.cc/ IRF7821 Static @ TJ = 25C (unless otherwise specified) Parameter Min. Typ. Max. Units Conditions BVDSS VDSS/TJ Drain-to-Source Breakdown Voltage Breakdown Voltage Temp. Coefficient 30 --- --- 0.025 --- --- V VGS = 0V, ID = 250A V/C Reference to 25C, ID = 1mA RDS(on) Static Drain-to-Source On-Resistance --- --- 7.0 9.5 9.1 12.5 m VGS(th) VGS(th) Gate Threshold Voltage Gate Threshold Voltage Coefficient 1.0 --- --- - 4.9 --- --- IDSS Drain-to-Source Leakage Current --- --- --- --- 1.0 150 A VDS = 24V, VGS = 0V VDS = 24V, VGS = 0V, TJ = 125C IGSS Gate-to-Source Forward Leakage Gate-to-Source Reverse Leakage --- --- --- --- 100 -100 nA VGS = 20V VGS = -20V gfs Qg Forward Transconductance Total Gate Charge 22 --- --- 9.3 --- 14 S VDS = 15V, ID = 10A Qgs1 Qgs2 Pre-Vth Gate-to-Source Charge Post-Vth Gate-to-Source Charge --- --- 2.5 0.8 --- --- Qgd Qgodr Gate-to-Drain Charge Gate Charge Overdrive Switch Charge (Qgs2 + Qgd) --- --- 2.9 3.1 --- --- Output Charge --- --- 3.7 6.1 --- --- td(on) tr td(off) Turn-On Delay Time Rise Time Turn-Off Delay Time --- --- --- 6.3 2.7 9.7 --- --- --- tf Ciss Fall Time Input Capacitance --- --- 7.3 1010 --- --- Coss Crss Output Capacitance Reverse Transfer Capacitance --- --- 360 110 --- --- Qsw Qoss VGS = 10V, ID = 13A VGS = 4.5V, ID = 10A e e V VDS = VGS, ID = 250A mV/C nC VDS = 15V VGS = 4.5V ID = 10A See Fig. 16 nC VDS = 10V, VGS = 0V ns VDD = 15V, VGS = 4.5V ID = 10A Clamped Inductive Load e VGS = 0V pF VDS = 15V = 1.0MHz Avalanche Characteristics EAS IAR Parameter Single Pulse Avalanche Energy Avalanche Current c Typ. --- --- dh Max. 44 10 Units mJ A Diode Characteristics Parameter Min. Typ. Max. Units IS Continuous Source Current --- --- 3.1 ISM (Body Diode) Pulsed Source Current --- --- 100 VSD trr (Body Diode) Diode Forward Voltage Reverse Recovery Time --- --- --- 28 1.0 42 V ns Qrr Reverse Recovery Charge --- 23 35 nC ch A 2 Conditions MOSFET symbol showing the integral reverse p-n junction diode. TJ = 25C, IS = 10A, VGS = 0V TJ = 25C, IF = 10A, VDD = 20V di/dt = 100A/s e e www.irf.com http://store.iiic.cc/ IRF7821 100 VGS 10V 4.5V 3.7V 3.5V 3.3V 3.0V 2.7V BOTTOM 2.5V 100 VGS 10V 4.5V 3.7V 3.5V 3.3V 3.0V 2.7V BOTTOM 2.5V TOP 10 1 2.5V ID, Drain-to-Source Current (A) ID, Drain-to-Source Current (A) TOP 10 2.5V 20s PULSE WIDTH Tj = 150C 20s PULSE WIDTH Tj = 25C 1 0.1 0.1 1 10 0.1 100 10 100 VDS, Drain-to-Source Voltage (V) VDS, Drain-to-Source Voltage (V) Fig 1. Typical Output Characteristics Fig 2. Typical Output Characteristics 2.0 TJ = 150C 10.0 T J = 25C 1.0 VDS = 15V 20s PULSE WIDTH 0.1 2.0 3.0 4.0 5.0 ID = 13A VGS = 10V 1.5 (Normalized) RDS(on) , Drain-to-Source On Resistance 100.0 ID, Drain-to-Source Current () 1 1.0 0.5 6.0 -60 -40 -20 0 20 40 60 80 100 120 140 160 T J , Junction Temperature (C) VGS, Gate-to-Source Voltage (V) Fig 3. Typical Transfer Characteristics www.irf.com Fig 4. Normalized On-Resistance Vs. Temperature 3 http://store.iiic.cc/ IRF7821 10000 12 VGS = 0V, f = 1 MHZ Ciss = C gs + Cgd, C ds SHORTED VGS , Gate-to-Source Voltage (V) ID= 10A C, Capacitance (pF) Crss = Cgd Coss = Cds + Cgd Ciss 1000 Coss Crss 100 8 6 4 2 0 10 1 10 0 100 5 1000 ID, Drain-to-Source Current (A) 100.0 1.0 T J = 25C OPERATION IN THIS AREA LIMITED BY R DS(on) 10 1 0.1 0.1 1.0 10msec Tc = 25C Tj = 150C Single Pulse 0.1 1.5 1.0 10.0 100.0 1000.0 VDS , Drain-toSource Voltage (V) VSD, Source-toDrain Voltage (V) Fig 7. Typical Source-Drain Diode Forward Voltage 100sec 1msec VGS = 0V 0.5 20 100 T J = 150C 0.0 15 Fig 6. Typical Gate Charge Vs. Gate-to-Source Voltage Fig 5. Typical Capacitance Vs. Drain-to-Source Voltage 10.0 10 Q G Total Gate Charge (nC) VDS, Drain-to-Source Voltage (V) ISD, Reverse Drain Current (A) VDS= 24V VDS= 15V 10 Fig 8. Maximum Safe Operating Area 4 www.irf.com http://store.iiic.cc/ IRF7821 2.6 VGS(th) Gate threshold Voltage (V) 14 ID , Drain Current (A) 12 10 8 6 4 2 2.2 1.8 ID = 250A 1.4 1.0 0 25 50 75 100 125 -75 150 -50 -25 0 25 50 75 100 125 150 T J , Temperature ( C ) T J , Junction Temperature (C) Fig 10. Threshold Voltage Vs. Temperature Fig 9. Maximum Drain Current Vs. Case Temperature 100 Thermal Response ( Z thJA ) D = 0.50 0.20 10 0.10 0.05 0.02 0.01 1 0.1 SINGLE PULSE ( THERMAL RESPONSE ) 0.01 1E-006 1E-005 0.0001 0.001 0.01 0.1 1 10 100 t1 , Rectangular Pulse Duration (sec) Fig 11. Maximum Effective Transient Thermal Impedance, Junction-to-Ambient www.irf.com 5 http://store.iiic.cc/ 30 100 ID = 13A 25 20 15 T J = 125C 10 T J = 25C 5 0 2.0 4.0 6.0 8.0 10.0 EAS, Single Pulse Avalanche Energy (mJ) RDS(on), Drain-to -Source On Resistance ( m) IRF7821 ID 4.5A TOP 8.0A BOTTOM 10A 80 60 40 20 0 25 VGS, Gate-to-Source Voltage (V) 50 75 100 125 150 Starting T J , Junction Temperature (C) Fig 13c. Maximum Avalanche Energy Vs. Drain Current Fig 12. On-Resistance Vs. Gate Voltage LD VDS 15V L VDS VDD DRIVER D.U.T D.U.T RG VGS 20V + V - DD IAS VGS Pulse Width < 1s Duty Factor < 0.1% A 0.01 tp Fig 13a. Unclamped Inductive Test Circuit V(BR)DSS Fig 14a. Switching Time Test Circuit VDS tp 90% 10% VGS td(on) I AS Fig 13b. Unclamped Inductive Waveforms tf td(off) tr Fig 14b. Switching Time Waveforms 6 www.irf.com http://store.iiic.cc/ IRF7821 D.U.T Driver Gate Drive P.W. + + - - * D.U.T. ISD Waveform Reverse Recovery Current + RG * * * * dv/dt controlled by RG Driver same type as D.U.T. I SD controlled by Duty Factor "D" D.U.T. - Device Under Test V DD P.W. Period VGS=10V Circuit Layout Considerations * Low Stray Inductance * Ground Plane * Low Leakage Inductance Current Transformer - D= Period + - Body Diode Forward Current di/dt D.U.T. VDS Waveform Diode Recovery dv/dt Re-Applied Voltage Body Diode VDD Forward Drop Inductor Curent ISD Ripple 5% * VGS = 5V for Logic Level Devices Fig 15. Peak Diode Recovery dv/dt Test Circuit for N-Channel HEXFET(R) Power MOSFETs Current Regulator Same Type as D.U.T. Id Vds Vgs 50K 12V .2F .3F D.U.T. + V - DS Vgs(th) VGS 3mA IG ID Qgs1 Qgs2 Qgd Qgodr Current Sampling Resistors Fig 16. Gate Charge Test Circuit Fig 17. Gate Charge Waveform www.irf.com 7 http://store.iiic.cc/ IRF7821 Power MOSFET Selection for Non-Isolated DC/DC Converters Control FET Synchronous FET Special attention has been given to the power losses in the switching elements of the circuit - Q1 and Q2. Power losses in the high side switch Q1, also called the Control FET, are impacted by the Rds(on) of the MOSFET, but these conduction losses are only about one half of the total losses. The power loss equation for Q2 is approximated by; * Ploss = Pconduction + Pdrive + Poutput ( 2 Ploss = Irms x Rds(on) ) Power losses in the control switch Q1 are given by; + (Qg x Vg x f ) Ploss = Pconduction+ Pswitching+ Pdrive+ Poutput Q + oss x Vin x f + (Qrr x Vin x f ) 2 This can be expanded and approximated by; *dissipated primarily in Q1. Ploss = (Irms 2 x Rds(on ) ) Qgs 2 Qgd +I x x Vin x f + I x x Vin x f ig ig + (Qg x Vg x f ) + Qoss x Vin x f 2 This simplified loss equation includes the terms Qgs2 and Qoss which are new to Power MOSFET data sheets. Qgs2 is a sub element of traditional gate-source charge that is included in all MOSFET data sheets. The importance of splitting this gate-source charge into two sub elements, Qgs1 and Qgs2, can be seen from Fig 16. Qgs2 indicates the charge that must be supplied by the gate driver between the time that the threshold voltage has been reached and the time the drain current rises to Idmax at which time the drain voltage begins to change. Minimizing Qgs2 is a critical factor in reducing switching losses in Q1. Qoss is the charge that must be supplied to the output capacitance of the MOSFET during every switching cycle. Figure A shows how Qoss is formed by the parallel combination of the voltage dependant (nonlinear) capacitances Cds and Cdg when multiplied by the power supply input buss voltage. 8 For the synchronous MOSFET Q2, Rds(on) is an important characteristic; however, once again the importance of gate charge must not be overlooked since it impacts three critical areas. Under light load the MOSFET must still be turned on and off by the control IC so the gate drive losses become much more significant. Secondly, the output charge Qoss and reverse recovery charge Qrr both generate losses that are transfered to Q1 and increase the dissipation in that device. Thirdly, gate charge will impact the MOSFETs' susceptibility to Cdv/dt turn on. The drain of Q2 is connected to the switching node of the converter and therefore sees transitions between ground and Vin. As Q1 turns on and off there is a rate of change of drain voltage dV/dt which is capacitively coupled to the gate of Q2 and can induce a voltage spike on the gate that is sufficient to turn the MOSFET on, resulting in shoot-through current . The ratio of Qgd/Qgs1 must be minimized to reduce the potential for Cdv/dt turn on. Figure A: Qoss Characteristic http://store.iiic.cc/ www.irf.com IRF7821 SO-8 Package Details ' ',0 % $ $ + >@ ( $ ;E >@ $ 0,//,0(7(56 0,1 0$; $ E F ' ( H %$6,& %$6,& H + %$6,& %$6,& . / \ $ ; H H ,1&+(6 0,1 0$; .[ & \ >@ ;/ ;F & $ % 127(6 ',0(16,21,1* 72/(5$1&,1*3(5$60(<0 &21752//,1*',0(16,210,//,0(7(5 ',0(16,216$5(6+2:1,10,//,0(7(56>,1&+(6@ 287/,1(&21)250672-('(&287/,1(06$$ ',0(16,21'2(6127,1&/8'(02/'3527586,216 02/'3527586,21612772(;&(('>@ ',0(16,21'2(6127,1&/8'(02/'3527586,216 02/'3527586,21612772(;&(('>@ ',0(16,21,67+(/(1*7+2)/($')2562/'(5,1*72 $68%675$7( )22735,17 ;>@ >@ ;>@ ;>@ SO-8 Part Marking (;$03/(7+,6,6$1,5) 026)(7 ,17(51$7,21$/ 5(&7,),(5 /2*2 <:: ;;;; ) '$7(&2'( <:: < /$67',*,72)7+(<($5 :: :((. /27&2'( 3$57180%(5 www.irf.com 9 http://store.iiic.cc/ IRF7821 SO-8 Tape and Reel TERMINAL NUMBER 1 12.3 ( .484 ) 11.7 ( .461 ) 8.1 ( .318 ) 7.9 ( .312 ) FEED DIRECTION NOTES: 1. CONTROLLING DIMENSION : MILLIMETER. 2. ALL DIMENSIONS ARE SHOWN IN MILLIMETERS(INCHES). 3. OUTLINE CONFORMS TO EIA-481 & EIA-541. 330.00 (12.992) MAX. 14.40 ( .566 ) 12.40 ( .488 ) NOTES : 1. CONTROLLING DIMENSION : MILLIMETER. 2. OUTLINE CONFORMS TO EIA-481 & EIA-541. Notes: Repetitive rating; pulse width limited by max. junction temperature. Starting TJ = 25C, L = 0.87mH RG = 25, IAS = 10A. Pulse width 400s; duty cycle 2%. When mounted on 1 inch square copper board R is measured at TJ approximately 90C Note: For the most current drawing please refer to IR website at http://www.irf.com/package/pkhexfet.html Data and specifications subject to change without notice. This product has been designed and qualified for the Industrial market. Qualification Standards can be found on IR's Web site. IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 Visit us at www.irf.com for sales contact information.05/2007 10 www.irf.com http://store.iiic.cc/