september 2000 ? 2000 fairchild semiconductor corporation FDS6984S rev c(w) FDS6984S dual notebook power supply n - channel powertrench ? ? ? ? syncfet ? general description the FDS6984S is designed to replace two single so-8 mosfets and schottky diode in synchronous dc:dc power supplies that provide various peripheral voltages for notebook computers and other battery powered electronic devices. FDS6984S contains two unique 30v, n-channel, logic level, powertrench mosfets designed to maximize power conversion efficiency. the high-side switch (q1) is designed with specific emphasis on reducing switching losses while the low- side switch (q2) is optimized to reduce conduction losses. q2 also includes an integrated schottky diode using fairchild?s monolithic syncfet technology. features ? q2 : optimized to minimize conduction losses includes syncfet schottky diode 8.5a, 30v r ds(on) = 19 m ? = @ v gs = 10v r ds(on) = 28 m ? = @ v gs = 4.5v ? q1 : optimized for low switching losses low gate charge ( 5 nc typical) 5.5a, 30v r ds(on) = 0.040 ? = @ v gs = 10v r ds(on) = 0.055 ? = @ v gs = 4.5v s2 so-8 g2 s1 g1 d2 d2 d1 d1 4 3 2 1 5 6 7 8 q1 q2 absolute maximum ratings t a = 25c unless otherwise noted symbol parameter q2 q1 units v dss drain-source voltage 30 30 v v gss gate-source voltage 20 20 v i d drain current - continuous (note 1a) 8.5 5.5 a - pulsed 30 20 p d power dissipation for dual operation 2 w power dissipation for single operation (note 1a) 1.6 (note 1b) 1 (note 1c) 0.9 t j , t stg operating and storage junction temperature range -55 to +150 c thermal characteristics r ja thermal resistance, junction-to-ambient (note 1a) 78 c/w r jc thermal resistance, junction-to-case (note 1) 40 c/w package marking and ordering information device marking device reel size tape width quantity FDS6984S FDS6984S 13? 12mm 2500 units FDS6984S
fds6680s rev c (w) electrical characteristics t a = 25c unless otherwise noted symbol parameter test conditions type min typ max units off characteristics v gs = 0 v, i d = 1 ma q2 30 bv dss drain-source breakdown voltage v gs = 0 v, i d = 250 a q1 30 v i dss zero gate voltage drain current v ds = 24 v, v gs = 0 v q2 q1 500 1 a i gssf gate-body leakage, forward v gs = 20 v, v ds = 0 v all 100 na i gssr gate-body leakage, reverse v gs = -20 v, v ds = 0 v all -100 na on characteristics (note 2) v gs(th) gate threshold voltage v ds = v gs , i d = 1 ma v ds = v gs , i d = 250 a q2 q1 1 1 3 3 v i d = 1 ma, referenced to 25 c q2 -6 ? v gs(th) === ? t j gate threshold voltage temperature coefficient i d = 250 ua, referenced to 25 c q1 -4 mv/ c v gs = 10 v, i d = 8.5 a v gs = 10 v, i d = 8.5 a, t j = 125 c v gs = 4.5 v, i d = 7 a q2 16 24 23 19 32 28 r ds(on) static drain-source on-resistance v gs = 10 v, i d = 5.5 a v gs = 10 v, i d = 5.5 a, t j = 125 c v gs = 4.5 v, i d = 4.6 a q1 35 53 48 40 60 55 m ? i d(on) on-state drain current v gs = 10 v, v ds = 5 v q2 q1 30 20 a g fs forward transconductance v ds = 5 v, i d = 8.5 a v ds = 5 v, i d = 5.5 a q2 q1 26 40 s dynamic characteristics c iss input capacitance q2 q1 1233 462 pf c oss output capacitance q2 q1 344 113 pf c rss reverse transfer capacitance v ds = 15 v, v gs = 0 v, f = 1.0 mhz q2 q1 106 40 pf switching characteristics (note 2) t d(on) turn-on delay time q2 q1 8 10 16 18 ns t r turn-on rise time q2 q1 5 14 10 25 ns t d(off) turn-off delay time q2 q1 25 21 40 34 ns t f turn-off fall time v dd = 15 v, i d = 1 a, v gs = 10v, r gen = 6 ? q2 q1 11 7 20 14 ns q g total gate charge q2 q1 11 8.5 16 12 nc q gs gate-source charge q2 q1 5 2.4 nc q gd gate-drain charge q2 v ds = 15 v, i d = 8.5 a, v gs =5v q1 v ds = 15 v, i d = 5.5 a, v gs = 5 v q2 q1 4 3.1 nc FDS6984S
fds6680s rev c (w) electrical characteristics (continued) t a = 25c unless otherwise noted symbol parameter test conditions type min typ max units drain?source diode characteristics and maximum ratings i s maximum continuous drain-source diode forward current q2 q1 3.0 1.3 a t rr reverse recovery time 17 ns q rr reverse recovery charge i f = 10a, d if /d t = 300 a/s (note 3) q2 12.5 nc v sd drain-source diode forward voltage v gs = 0 v, i s = 3.5 a (note 2) v gs = 0 v, i s = 1.3 a (note 2) q2 q1 0.5 0.74 0.7 1.2 v notes: 1. r ja is the sum of the junction-to-case and case-to-ambient thermal resistance where the case thermal reference is defined as the so lder mounting surface of the drain pins. r jc is guaranteed by design while r ca is determined by the user's board design. a) 78c/w when mounted on a 0.5in 2 pad of 2 oz copper b) 125c/w when mounted on a 0.02 in 2 pad of 2 oz copper c) 135c/w when mounted on a minimum pad. scale 1 : 1 on letter size paper 2. see ?syncfet schottky body diode characteristics? below. 3. pulse test: pulse width < 300 s, duty cycle < 2.0% FDS6984S
fds6680s rev c (w) typical characteristics: q2 0 10 20 30 40 50 0123 v ds , drain-source voltage (v) 5.0v 4.5v 4.0v 3.5v v gs = 10v 6.0v 0.6 1 1.4 1.8 2.2 2.6 0 1020304050 i d , drain current (a) v gs = 4.0v 6.0v 8.0v 10v 5.0v 4.5v figure 1. on-region characteristics. figure 2. on-resistance variation with drain current and gate voltage. 0.4 0.7 1 1.3 1.6 1.9 -50 -25 0 25 50 75 100 125 150 t j , junction temperature ( o c) i d = 10a v gs = 10v 0 0.01 0.02 0.03 0.04 0.05 0.06 246810 v gs , gate to source voltage (v) i d = 5a t a = 125 o c t a = 25 o c figure 3. on-resistance variation with temperature. figure 4. on-resistance variation with gate-to-source voltage. 0 10 20 30 40 50 1.5 2.5 3.5 4.5 5.5 v gs , gate to source voltage (v) t a = -55 o c 25 o c 125 o c v ds = 5v 0.001 0.01 0.1 1 10 0 0.2 0.4 0.6 0.8 v sd , body diode forward voltage (v) t a = 125 o c 25 o c -55 o c v gs = 0v figure 5. transfer characteristics. figure 6. body diode forward voltage variation with source current and temperature. FDS6984S
fds6680s rev c (w) typical characteristics: q2 0 2 4 6 8 10 036912151821 q g , gate charge (nc) i d =10a v ds = 5v 15v 10v 0 400 800 1200 1600 2000 0 5 10 15 20 25 30 v ds , drain to source voltage (v) c iss c rss c oss f = 1mhz v gs = 0 v figure 7. gate charge characteristics. figure 8. capacitance characteristics. 0.01 0.1 1 10 100 0.1 1 10 100 v ds , drain-source voltage (v) dc 10s 1s 100ms 100 ja = 135 o c/w t a = 25 o c 10ms 1ms 0 10 20 30 40 50 0.001 0.01 0.1 1 10 100 1000 t 1 , time (sec) single pulse r ja = 135c/w t a = 25c figure 9. maximum safe operating area. figure 10. single pulse maximum power dissipation. FDS6984S
fds6680s rev c (w) typical characteristics q1 0 10 20 30 40 012345 v ds , drain-source voltage (v) 4.0v 3.0 3.5v 4.5 v gs = 10v 5.0 6.0 0.5 1 1.5 2 2.5 3 0102030 i d , drain current (a) v gs = 3.0v 4.0v 3.5v 10v 4.5v 5.0v 6.0v figure 11. on-region characteristics. figure 12. on-resistance variation with drain current and gate voltage. 0.6 0.8 1 1.2 1.4 1.6 1.8 -50 -25 0 25 50 75 100 125 150 t j , junction temperature ( o c) i d = 4.6a v gs = 10v 0 0.05 0.1 0.15 0.2 2.533.544.55 v gs , gate to source voltage (v) i d = 2.3 a t a = 125 o c t a = 25 o c figure 13. on-resistance variation with temperature. figure 14. on-resistance variation with gate-to-source voltage. 0 5 10 15 20 25 12345 v gs , gate to source voltage (v) t a = -55 o c 25 o c 125 o c v ds = 5v 0.001 0.01 0.1 1 10 100 0 0.2 0.4 0.6 0.8 1 1.2 1.4 v sd , body diode forward voltage (v) t a = 125 o c 25 o c -55 o c v gs = 0v figure 15. transfer characteristics. figure 16. body diode forward voltage variation with source current and temperature. FDS6984S
fds6680s rev c (w) typical characteristics q1 0 2 4 6 8 10 0246810 q g , gate charge (nc) i d = 4.6a v ds = 5v 15v 10v 0 100 200 300 400 500 600 700 0 5 10 15 20 25 30 v ds , drain to source voltage (v) c iss c rss c oss f = 1mhz v gs = 0 v figure 17. gate charge characteristics. figure 18. capacitance characteristics. 0.01 0.1 1 10 100 0.1 1 10 100 v ds , drain-source voltage (v) dc 10s 1s 100ms r ds(on) limit v gs = 10v single pulse r ja = 135 o c/w t a = 25 o c 10ms 1ms 100s 0 10 20 30 0.01 0.1 1 10 100 t 1 , time (sec) single pulse r ja = 135c/w t a = 25c figure 19. maximum safe operating area. figure 20. single pulse maximum power dissipation. 0.0001 0.001 0.01 0.1 1 10 100 300 0.001 0.002 0.005 0.01 0.02 0.05 0.1 0.2 0.5 1 t , time (s ec) tran sien t t hermal resistance r(t) , no rmalized effective 1 single pulse d = 0.5 0. 1 0.05 0.02 0.01 0. 2 duty cycle, d = t /t 1 2 r (t) = r(t) * r r = 135 c/w ja ja ja t - t = p * r (t) ja a j p(p k ) t 1 t 2 figure 21. transient thermal response curve. thermal characterization performed using the conditions described in note 1c. transient thermal response will change depending on the circuit board design. FDS6984S
fds6680s rev c (w) typical characteristics (continued) syncfet schottky body diode characteristics fairchild?s syncfet 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 22 shows the reverse recovery characteristic of the FDS6984S. figure 22. FDS6984S syncfet body diode reverse recovery characteristic. for comparison purposes, figure 23 shows the reverse recovery characteristics of the body diode of an equivalent size mosfet produced without syncfet (fds6690a). figure 23. non-syncfet (fds6690a) body diode reverse recovery characteristic. schottky barrier diodes exhibit significant leakage at high temperature and high reverse voltage. this will increase the power in the device. 0.00001 0.0001 0.001 0.01 0.1 0 10 20 30 v ds , reverse voltage (v) i dss , reverse le akage current (a) 125 o c 25 o c figure 24. syncfet body diode reverse leakage versus drain-source voltage and temperature. 10ns/div 3a/div FDS6984S 10ns/div 3a/div 0v
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