Fairchild FDS6994S service manual
October
FDS6994S
2006
FDS6994S
Dual Notebook Power Supply N-Channel PowerTrench
General Description
The FDS6994S 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. FDS6994S 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
using Fairchild’s monolithic SyncFET technology.
D1
D1
D2
D2
G1
S2
S1
G2
SO-8
Features
• Q2: Optimized to minimize conduction losses
Includes SyncFET Schottky body diode
8.2A, 30V R
R
• Q1: Optimized for low switching losses
Low gate charge (85.5 nC typical)
6.9A, 30V R
R
5
6
7
8
SyncFet™
= 15 mΩ @ VGS = 10V
DS(on)
= 17.5 mΩ @ VGS = 4.5V
DS(on)
= 21 mΩ @ VGS = 10V
DS(on)
= 26 mΩ @ VGS = 4.5V
DS(on)
4
Q1
Q2
3
2
1
Absolute Maximum Ratings T
= 25°C unless otherwise noted
A
Symbol Parameter Q2 Q1 Units
V
Drain-Source Voltage 30 30 V
DSS
V
Gate-Source Voltage
GSS
ID Drain Current - Continuous
- Pulsed 30 20
PD Power Dissipation for Dual Operation 2 W
Power Dissipation for Single Operation
TJ, T
STG
Operating and Storage Junction Temperature Range -55 to +150
(Note 1a)
8.2 6.9 A
(Note 1a)
1.6
(Note 1b)
(Note 1c)
±16 ±16
1
0.9
V
°C
Thermal Characteristics
R
θJA
R
θJC
Thermal Resistance, Junction-to-Ambient
Thermal Resistance, Junction-to-Case
Package Marking and Ordering Information
Device Marking Device Reel Size Tape width Quantity
FDS6994S FDS6994S 13” 12mm 2500 units
2006 Fairchild Semiconductor Corporation
(Note 1a)
(Note 1)
78
40
°C/W
°C/W
FDS6994S Rev C2(W)
FDS6994S
Electrical Characteristics T
Symbol
Parameter Test Conditions Type Min Typ Max Units
= 25°C unless otherwise noted
A
Off Characteristics
BV
Drain-Source Breakdown
DSS
Voltage
∆BV
∆T
I
Zero Gate Voltage Drain
DSS
Breakdown Voltage
DSS
Temperature Coefficient
J
Current
I
Gate-Body Leakage VGS = ±16 V, VDS = 0 V All ±100
GSS
On Characteristics
V
Gate Threshold Voltage VDS = VGS, ID = 1 mA
GS(th)
∆V
∆TJ
RD
S(on)
Gate Threshold Voltage
GS(th)
Temperature Coefficient
Static Drain-Source
(Note 2)
On-Resistance
I
On-State Drain Current VGS = 10 V, VDS = 5 V Q2
D(on)
gFS Forward Transconductance VDS = 10 V, ID = 8.2 A
VGS = 0 V, ID = 1 mA
V
= 0 V, ID = 250 uA
GS
I
= 1 mA, Referenced to 25°C
D
= 250 µA, Referenced to 25°C
I
D
VDS = 24 V, VGS = 0 V Q2
V
= VGS, ID = 250 µA
DS
I
= 1 mA, Referenced to 25°C
D
= 250 uA, Referenced to 25°C
I
D
VGS = 10 V, ID = 8.2A
= 10 V, ID = 8.2 A, TJ = 125°C
V
GS
V
= 4.5 V, ID = 7.6 A
GS
V
= 10 V, ID = 6.9 A
GS
= 10 V, ID = 6.9 A, TJ = 125°C
V
GS
V
= 4.5 V, ID = 6.2 A
GS
= 10 V, ID = 6.9 A
V
DS
Q2
30
Q1
30
Q2
Q1
23
24
500
Q1
Q2
Q1 1 1
Q2
Q1
1.5
1.9 3 3
–2
–5
Q2 10
15
11
Q1 16
24
19
Q1
Q2
Q1
30
20
42
41
Dynamic Characteristics
C
Input Capacitance Q2
iss
= 15 V, VGS = 0 V,
V
DS
f = 1.0 MHz
C
Output Capacitance Q2
oss
C
Reverse Transfer Capacitance
rss
RG Gate Resistance VGS = 15 mV, f = 1.0 MHz Q2
Q1
Q1
Q2
Q1
Q1
2815
800
540
205
210
90
2.844444.9
2.6 4.6
V
mV/°C
µA
1
nA
V
mV/°C
15
24
17.5
mΩ
21
33.5
26
A
S
pF
pF
pF
Ω
FDS6994S Rev C2(W)
Electrical Characteristics
Symbol
Parameter
(continued)
T
Test Conditions
= 25°C unless otherwise noted
A
Type
Min
Typ Max Units
Switching Characteristics
t
Turn-On Delay Time
d(on)
tr Turn-On Rise Time
t
Turn-Off Delay Time
d(off)
tf Turn-Off Fall Time
Qg Tot al Gate Charge
Qgs Gate-Source Charge
Qgd Gate-Drain Charge
Drain–Source Diode Characteristics and Maximum Ratings
IS Maximum Continuous Drain-Source Diode Forward Current Q2
(Note 2)
V
= 15 V, ID = 1 A,
DD
= 10V, R
V
GS
GEN
= 6 Ω
Q2:
V
= 15 V, ID = 7.9 A, VGS = 5 V
DS
Q1:
V
= 15 V, ID = 6.5 A, VGS = 5 V
DS
Q2
Q1
Q2
11
11
8 7 16
Q1
Q2
Q1
Q2
50
27
17 4 31 8 ns
Q1
Q2
25 8 35
Q1
Q2
6 3 nC
Q1
Q2
7 3 nC
Q1
2.3
Q1
tRR Reverse Recovery Time
QRR Revers e Recovery Charge
tRR Reverse Recovery Time
QRR Revers e Recovery Charge
VSD Drain-Source Diode Forward
Voltage
Notes:
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
1. R
θJA
the drain pins. R
is guaranteed by design while R
θJC
= 8.2 A,
I
F
= 300 A/µs
d
iF/dt
= 6.9 A,
I
F
= 100 A/µs
d
iF/dt
VGS = 0 V, IS = 2.3 A
VGS = 0 V, IS = 1.3 A
is determined by the user's board design.
θCA
(Note 3)
(Note 3)
(Note 2)
(Note 2)
Q2
Q2
Q2
Q1
25
19 nC
23
10 nC
0.4
0.53
20
ns
20
ns
14
80
43
ns
nC
12
A
1.3
ns
ns
7
1.2
V
a) 78°C/W when
mounted on a
2
0.5in
pad of 2
oz copper
Scale 1 : 1 on letter size paper
2. Pulse Test: Pulse Width < 300µs, Duty Cycle < 2.0%
3. See “SyncFET Schottky body diode characteristics” below.
b) 125°C/W when
mounted on a
2
pad of
0.02 in
2 oz copper
c) 135°C/W when
mounted on a
minimum pad.
FDS6994S Rev C2(W)
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