Fairchild Semiconductor FDS6984S Datasheet

PRELIMINARY

FDS6984S

FDS6984S

Dual Notebook Power Supply N-Channel PowerTrench SyncFET

May 2000

™

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 low­side switch (Q2) is optimized to reduce conduction
losses. Q2 also includes an integrated Schottky diode

Features

• Q2: Optimized to minimize conduction losses
Includes SyncFET Schottky diode

8.5A, 30V R

• Q1: Optimized for low switching losses
Low gate charge ( 5 nC typical)

5.5A, 30V R
R

= 0.019Ω @ V

DS(on)

R

= 0.027Ω @ V

DS(on)

= 0.040Ω @ V

DS(on)

= 0.055Ω @ V

DS(on)

= 10V

GS

= 4.5V

GS

= 10V

GS

= 4.5V

GS

using Fairchild’s monolithic SyncFET technology.

4
3
2
1

Absolute Maximum Ratings T

= 25°C unless otherwise noted

A

5

Q1

6
7

Q2

8

Symbol Parameter Q2 Q1 Units

V

DSS

V

GSS

I

D

P

D

TJ, T

STG

Drain-Source Voltage 30 30 V
Gate-Source Voltage

±20 ±20

Drain Current - Continuous (Note 1a) 8.5 5.5 A

- Pulsed 30 20
Power Dissipation for Dual Operation 2 W
Power Dissipation for Single Operation (Note 1a) 1.6

(Note 1b)
(Note 1c)

1

0.9

Operating and Storage Junction Temperature Range -55 to +150

V

°C

Thermal Characteristics

R

θJA

R

θJC

Thermal Resistance, Junction-to-Ambient (Note 1a) 78
Thermal Resistance, Junction-to-Case (Note 1) 40

Package Marking and Ordering Information

Device Marking Device Reel Size Tape width Quantity

FDS6984S FDS6984S 13” 12mm 2500 units

2000 Fairchild Semiconductor Corporation

°C/W
°C/W

FDS6984S Rev B(W)

Electrical Characteristics T

FDS6984S

= 25°C unless otherwise noted

A

Symbol Parameter Test Conditions Type Min Typ Max Units
Off Characteristics

VGS = 0 V, ID = 1 mA Q2 30BV
VGS = 0 V, ID = 250 µA Q1 30

VDS = 24 V, VGS = 0 V Q2

Q1

1000

1

V

µA

I

DSS

I

GSSF

I

GSSR

DSS

Drain-Source Breakdown
Voltage

Zero Gate Voltage Drain
Current

Gate-Body Leakage, Forward VGS = 20 V, VDS = 0 V All 100 nA
Gate-Body Leakage, Reverse VGS = -20 V, VDS = 0 V All -100 nA

On Characteristics (Note 2)

V

GS(th)

∆VGS(th)
∆T

R

DS(on)

I

D(on)

g

FS

Gate Threshold Voltage VDS = VGS, ID = 1 mA

VDS = VGS, ID = 250 µA

Gate Threshold Voltage
Temperature Coefficient

J

Static Drain-Source
On-Resistance

ID = 1 mA, Referenced to 25°C
ID = 250 uA, Referenced to 25°C
VGS = 10 V, ID = 8.5 A

VGS = 10 V, ID = 8.5 A, TJ = 125°C
VGS = 4.5 V, ID = 7 A

VGS = 10 V, ID = 5.5 A
VGS = 10 V, ID = 5.5 A, TJ = 125°C
VGS = 4.5 V, ID = 4.6 A

On-State Drain Current VGS = 10 V, VDS = 5 V Q2Q130
Forward Transconductance VDS = 5 V, ID = 8.5 A

VDS = 5 V, ID = 5.5 A

Q2Q11

1

Q2 -6
Q1 -4
Q2 16

24
23

Q1 35

53
48

20
Q2
Q1

26
40

19
32
27

40
60
55

3

V

3

mV/°C

mΩ

A
S

Dynamic Characteristics

C

iss

C

oss

C

rss

Input Capacitance Q2

VDS = 15 V, VGS = 0 V,
f = 1.0 MHz

Q1

Output Capacitance Q2

Q1

Reverse Transfer Capacitance

Q2
Q1

1233

462
344

113
106

40

pF
pF
pF

Switching Characteristics (Note 2)

t
t
t
t
Q
Q
Q

d(on)

r

d(off)

f

g

gs

gd

Turn-On Delay Time Q2

VDD = 15 V, ID = 1 A,
VGS = 10V, R

GEN

= 6 Ω

Q1

Turn-On Rise Time Q2

Q1

Turn-Off Delay Time Q2

Q1

Turn-Off Fall Time

Q2
Q1

Total Gate Charge Q2

Q2
VDS = 15 V, ID = 8.5 A, VGS =5V

Q1

Gate-Source Charge Q2
Gate-Drain Charge

Q1
VDS = 15 V, ID = 5.5 A,VGS = 5 V

Q1
Q2
Q1

8

1618ns

10

5

1025ns

14
25

4034ns

21
11

2014ns

7

11

8.51812
5

2.4
4

3.1

nC
nC
nC

FDS6680S Rev B (W)

Electrical Characteristics (continued) T

FDS6984S

= 25°C unless otherwise noted

A

Symbol Parameter Test Conditions Type Min Typ Max Units
Drain–Source Diode Characteristics and Maximum Ratings

I

S

t

rr

Q

rr

V

SD

Notes:

1. R

θJA

the drain pins. R

Maximum Continuous Drain-Source Diode Forward Current Q2

Q1

Reverse Recovery Time 17
Reverse Recovery Charge

Drain-Source Diode Forward
Voltage

is the sum of the junction-to-case and case-to-ambient thermal resistance where the case thermal reference is defined as the solder mounting surface of

is guaranteed by design while R

θJC

IF = 10A,
diF/dt = 300 A/µs (Note 3)

VGS = 0 V, IS = 3.5 A (Note 2)
VGS = 0 V, IS = 1.3 A (Note 2)Q2Q1

is determined by the user's board design.

θCA

Q2

12.5 nC

0.74

0.5

3.0

1.3
ns

0.7

1.2

A

V

a) 78°/W when

mounted on a

0.5 in2 pad of 2 oz
copper

Scale 1 : 1 on letter size paper

2. 2. See “SyncFET Schottky body diode characteristics” below.

3. Pulse Test: Pulse Width < 300µs, Duty Cycle < 2.0%

b) 125°/W when

mounted on a .02 in
pad of 2 oz copper

2

c) 135°/W when mounted on a

minimum pad.

FDS6680S Rev B (W)

Typical Characteristics: Q2

5.0V

4.0V

3.5V

6.0V

6.0V

8.0V

10V

5.0V

VDS = 5V

TA = 125oC

25oC

-55oC

FDS6984S

50

VGS = 10V

40

30

20

10

0

0 1 2 3

VDS, DRAIN-SOURCE VOLTAGE (V)

2.6
VGS = 4.0V

2.2

1.8

1.4

1

0.6

0 10 20 30 40 50

ID, DRAIN CURRENT (A)

Figure 1. On-Region Characteristics. Figure 2. On-Resistance Variation with

Drain Current and Gate Voltage.

1.9
ID = 10A

VGS = 10V

1.6

1.3

1

0.7

0.4

-50 -25 0 25 50 75 100 125 150

TJ, JUNCTION TEMPERATURE (oC)

0.06

0.05

0.04

0.03

0.02

0.01

0

2 4 6 8 10

TA = 25oC

VGS, GATE TO SOURCE VOLTAGE (V)

TA = 125oC

ID = 5A

Figure 3. On-Resistance Variation with

Temperature.

50

40

30

20

10

0

1.5 2.5 3.5 4.5 5.5

VGS, GATE TO SOURCE VOLTAGE (V)

TA = -55oC

o

o

Figure 4. On-Resistance Variation with

Gate-to-Source Voltage.

10

VGS = 0V

1

0.1

0.01

0.001
0 0.2 0.4 0.6 0.8

VSD, BODY DIODE FORWARD VOLTAGE (V)

Figure 5. Transfer Characteristics. Figure 6. Body Diode Forward Voltage Variation

with Source Current and Temperature.

FDS6680S Rev B (W)

Typical Characteristics: Q2

ID =10A

VDS = 5V

15V

10V

VGS = 0 V

DC

10s

1s

µ

10ms

1ms

FDS6984S

10

8

6

4

2

0

0 3 6 9 12 15 18 21

Qg, GATE CHARGE (nC)

2000

1600

1200

800

400

0

0 5 10 15 20 25 30

VDS, DRAIN TO SOURCE VOLTAGE (V)

CISS

COSS

CRSS

Figure 7. Gate Charge Characteristics. Figure 8. Capacitance Characteristics.

100

RDS(ON) LIMIT

10

100ms

1

VGS = 10V

SINGLE PULSE

0.1

0.01

0.1 1 10 100

θ

R

JA = 135

TA = 25oC

o

C/W

VDS, DRAIN-SOURCE VOLTAGE (V)

50

40

30

20

10

0

0.001 0.01 0.1 1 10 100 1000

t1, TIME (sec)

SINGLE PULSE
RθJA = 135°C/W

TA = 25°C

f = 1MHz

Figure 9. Maximum Safe Operating Area. Figure 10. Single Pulse Maximum

Power Dissipation.

FDS6680S Rev B (W)