AO4938
30V Dual N-Channel MOSFET
SRFET
General Description
The AO4938 uses advanced trench technology to provide
excellent R
DS(ON)
and low gate charge. The two MOSFETs
make a compact and efficient switch and synchronous
rectifier combination for use in DC-DC converters. A
monolithically integrated Schottky diode in parallel with
the synchronous MOSFET to boost efficiency further.
TM
Product Summary
FET1(N-Channel)
V
DS
= 30V
I
D
= 8.8A (V
GS
=10V)
R
DS(ON)
< 16m
< 22m
(V
GS
=10V)
(V
GS
=4.5V)
FET2(N-Channel)
30V
8A (V
GS
=10V)
R
DS(ON)
< 19m
< 28m
(V
GS
=10V)
(V
GS
=4.5V)
100% UIS Tested
100% R
g
Tested
ESD Protected
100% UIS Tested
100% R
g
Tested
SOIC-8
Top View
Bottom View
Top View
D2
D2
G1
S1
G2
S2/D1
S2/D1
S2/D1
SRFET
TM
Soft Recovery
MOSFET:
Integrated Schottky Diode
D1
D2
G2
G1
S1
S2
Pin1
Absolute Maximum Ratings T
A
=25° unless otherwise noted
C
Parameter
Symbol
Max FET1
Drain-Source Voltage
V
DS
30
Gate-Source Voltage
Continuous Drain
Current
Pulsed Drain Current
Avalanche Current
C
C
Max FET2
30
±20
8
6.5
40
13
25
2
1.3
Units
V
V
A
A
mJ
W
°
C
V
GS
T
A
=25°
C
T
A
=70°
C
C
±20
8.8
7.1
60
21
66
2
1.3
-55 to 150
I
D
I
DM
I
AS
, I
AR
E
AS
, E
AR
P
D
T
J
, T
STG
Avalanche energy L=0.3mH
Power Dissipation
B
T
A
=25°
C
T
A
=70°
C
Junction and Storage Temperature Range
Thermal Characteristics
Parameter
Maximum Junction-to-Ambient
A
Maximum Junction-to-Ambient
A D
Maximum Junction-to-Lead
Symbol
t
≤
10s
Steady-State
Steady-State
R
θJA
R
θJL
Typ
48
74
32
Max
62.5
90
40
Units
°
C/W
°
C/W
°
C/W
Rev 3: Mar. 2011
www.aosmd.com
Page 1 of 8
AO4938
FET1 Electrical Characteristics (T
J
=25° unless otherwise noted)
C
Symbol
Parameter
Conditions
I
D
=250uA, V
GS
=0V
V
DS
=30V, V
GS
=0V
T
J
=125°
C
V
DS
=0V, V
GS
=±20V
V
DS
=V
GS
I
D
=250µA
V
GS
=10V, V
DS
=5V
V
GS
=10V, I
D
=8.8A
R
DS(ON)
g
FS
V
SD
I
S
Static Drain-Source On-Resistance
V
GS
=4.5V, I
D
=7A
Forward Transconductance
Diode Forward Voltage
V
DS
=5V, I
D
=8.8A
I
S
=1A,V
GS
=0V
T
J
=125°
C
1.1
60
13.3
20
18
29
0.41
0.5
3.5
1267
V
GS
=0V, V
DS
=15V, f=1MHz
V
GS
=0V, V
DS
=0V, f=1MHz
308
118
1.3
21
V
GS
=10V, V
DS
=15V, I
D
=8.8A
10.4
3
3.6
5.2
V
GS
=10V, V
DS
=15V, R
L
=1.7Ω,
R
GEN
=3Ω
I
F
=8.8A, dI/dt=300A/µs
3.8
21.2
4.4
11.2
10.5
15
2.0
30
1600
16
25
22
1.65
Min
30
0.1
20
100
2.2
Typ
Max
Units
V
mA
nA
V
A
mΩ
mΩ
S
V
A
pF
pF
pF
Ω
nC
nC
nC
nC
ns
ns
ns
ns
ns
nC
STATIC PARAMETERS
BV
DSS
Drain-Source Breakdown Voltage
I
DSS
I
GSS
V
GS(th)
I
D(ON)
Zero Gate Voltage Drain Current
Gate-Body leakage current
Gate Threshold Voltage
On state drain current
Maximum Body-Diode + Schottky Continuous Current
DYNAMIC PARAMETERS
C
iss
Input Capacitance
C
oss
C
rss
R
g
Output Capacitance
Reverse Transfer Capacitance
Gate resistance
SWITCHING PARAMETERS
Q
g
(10V) Total Gate Charge
Q
g
(4.5V) Total Gate Charge
Q
gs
Q
gd
t
D(on)
t
r
t
D(off)
t
f
t
rr
Q
rr
Gate Source Charge
Gate Drain Charge
Turn-On DelayTime
Turn-On Rise Time
Turn-Off DelayTime
Turn-Off Fall Time
Body Diode Reverse Recovery Time
Body Diode Reverse Recovery Charge I
F
=8.8A, dI/dt=300A/µs
A. The value of R
θJA
is measured with the device mounted on 1in
2
FR-4 board with 2oz. Copper, in a still air environment with T
A
=25°C. The value
in any given application depends on the user's specific board design.
B. The power dissipation P
D
is based on T
J(MAX)
=150°C, using
≤
10s junction-to-ambient thermal resistance.
C. Repetitive rating, pulse width limited by junction temperature T
J(MAX)
=150°C. Ratings are based on low frequency and duty cycles to keep
initialT
J
=25°C.
D. The R
θJA
is the sum of the thermal impedence from junction to lead R
θJL
and lead to ambient.
E. The static characteristics in Figures 1 to 6 are obtained using <300µs pulses, duty cycle 0.5% max.
F. These curves are based on the junction-to-ambient thermal impedence which is measured with the device mounted on 1in
2
FR-4 board with 2oz.
Copper, assuming a maximum junction temperature of T
J(MAX)
=150°C. The SOA curve provides a single pulse rating.
THIS PRODUCT HAS BEEN DESIGNED AND QUALIFIED FOR THE CONSUMER MARKET. APPLICATIONS OR USES AS CRITICAL
COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS ARE NOT AUTHORIZED. AOS DOES NOT ASSUME ANY LIABILITY ARISING
OUT OF SUCH APPLICATIONS OR USES OF ITS PRODUCTS. AOS RESERVES THE RIGHT TO IMPROVE PRODUCT DESIGN,
FUNCTIONS AND RELIABILITY WITHOUT NOTICE.
Rev 3: Mar. 2011
www.aosmd.com
Page 2 of 8
AO4938
FET1: TYPICAL ELECTRICAL AND THERMAL CHARACTERISTICS
100
10V
80
7V
60
I
D
(A)
4V
40
3.5V
20
V
GS
=3V
0
0
1
2
3
4
5
V
DS
(Volts)
Fig 1: On-Region Characteristics (Note E)
20
18
R
DS(ON)
(mΩ)
Ω
V
GS
=4.5V
16
14
12
10
0
15
20
25
30
I
D
(A)
Figure 3: On-Resistance vs. Drain Current and Gate
Voltage (Note E)
5
10
V
GS
=10V
Normalized On-Resistance
1.8
1.6
1.4
1.2
1
0.8
0
75
100
125
150
175
Temperature (°
C)
0
Figure 4: On-Resistance vs. Junction Temperature
18
(Note E)
25
50
V
GS
=10V
I
D
=8.8A
10
5
0
1
2
3
4
5
V
GS
(Volts)
Figure 2: Transfer Characteristics (Note E)
125°C
25°C
I
D
(A)
15
4.5V
20
6V
5V
25
30
V
DS
=5V
17
5
2
V
GS
=4.5V
10
I
D
=7A
40
I
D
=8.8A
35
30
R
DS(ON)
(mΩ)
Ω
I
S
(A)
25
20
15
25°C
10
5
6
8
10
V
GS
(Volts)
Figure 5: On-Resistance vs. Gate-Source Voltage
(Note E)
2
4
125°C
1.0E+02
1.0E+01
1.0E+00
1.0E-01
1.0E-02
1.0E-03
1.0E-04
1.0E-05
0.4
0.6
0.8
1.0
V
SD
(Volts)
Figure 6: Body-Diode Characteristics (Note E)
0.0
0.2
25°C
125°C
40
Rev 3: Mar. 2011
www.aosmd.com
Page 3 of 8
AO4938
FET1: TYPICAL ELECTRICAL AND THERMAL CHARACTERISTICS
10
V
DS
=15V
I
D
=8.8A
8
Capacitance (pF)
V
GS
(Volts)
1500
C
iss
2000
6
1000
C
oss
500
4
2
C
rss
0
15
20
25
(Volts)
Figure 8: Capacitance Characteristics
DS
0
0
10
15
20
Q
g
(nC)
Figure 7: Gate-Charge Characteristics
5
25
0
5
10
V
30
100.0
1000
R
DS(ON)
limited
10µs
Power (W)
100µs
1ms
10ms
T
A
=25°C
10.0
100
I
D
(Amps)
1.0
10
0.1
T
J(Max)
=150°C
T
A
=25°C
DC
10s
0.0
0.01
0.1
1
V
DS
(Volts)
10
100
1
0.00001
0.001
0.1
10
1000
Pulse Width (s)
Figure 10: Single Pulse Power Rating Junction-
to-Ambient (Note F)
Figure 9: Maximum Forward Biased
Safe Operating Area (Note F)
10
Z
θ
JA
Normalized Transient
Thermal Resistance
D=T
on
/T
T
J,PK
=T
A
+P
DM
.Z
θJA
.R
θJA
1
R
θJA
=90°C/W
In descending order
D=0.5, 0.3, 0.1, 0.05, 0.02, 0.01, single pulse
0.1
0.01
Single Pulse
P
D
T
on
T
100
1000
0.001
0.00001
0.0001
0.01
0.1
1
10
Pulse Width (s)
Figure 11: Normalized Maximum Transient Thermal Impedance (Note F)
0.001
Rev 3: Mar. 2011
www.aosmd.com
Page 4 of 8
AO4938
FET2 Electrical Characteristics (T
J
=25° unless otherwise noted)
C
Symbol
Parameter
Conditions
Min
30
1
Typ
Max
Units
V
5
10
1.2
40
15.5
19
25
28
1
2.5
600
V
GS
=0V, V
DS
=15V, f=1MHz
V
GS
=0V, V
DS
=0V, f=1MHz
77
50
0.5
12
V
GS
=10V, V
DS
=15V, I
D
=8A
6
2
2
V
GS
=10V, V
DS
=15V, R
L
=1.8Ω,
R
GEN
=3Ω
I
F
=8A, dI/dt=500A/µs
1in
2
STATIC PARAMETERS
Drain-Source Breakdown Voltage
BV
DSS
I
DSS
I
GSS
V
GS(th)
I
D(ON)
R
DS(ON)
g
FS
V
SD
I
S
Zero Gate Voltage Drain Current
Gate-Body leakage current
Gate Threshold Voltage
On state drain current
Static Drain-Source On-Resistance
Forward Transconductance
Diode Forward Voltage
I
D
=250µA, V
GS
=0V
V
DS
=30V, V
GS
=0V
T
J
=55°C
V
DS
=0V, V
GS
= ±16V
µA
µA
V
A
V
DS
=V
GS
I
D
=250µA
V
GS
=10V, V
DS
=5V
V
GS
=10V, I
D
=8A
T
J
=125°C
V
GS
=4.5V, I
D
=4A
V
DS
=5V, I
D
=8A
I
S
=1A,V
GS
=0V
1.8
2.4
21
18.6
30
0.75
mΩ
mΩ
S
V
A
pF
pF
pF
Ω
nC
nC
nC
nC
ns
ns
ns
ns
Maximum Body-Diode Continuous Current
740
110
82
1.1
15
7.5
2.5
3
5
3.5
19
3.5
6
14
8
18
DYNAMIC PARAMETERS
C
iss
Input Capacitance
C
oss
C
rss
R
g
Output Capacitance
Reverse Transfer Capacitance
Gate resistance
888
145
115
1.7
18
9
3
5
SWITCHING PARAMETERS
Q
g
(10V) Total Gate Charge
Q
g
(4.5V) Total Gate Charge
Q
gs
Q
gd
t
D(on)
t
r
t
D(off)
t
f
t
rr
Q
rr
Gate Source Charge
Gate Drain Charge
Turn-On DelayTime
Turn-On Rise Time
Turn-Off DelayTime
Turn-Off Fall Time
Body Diode Reverse Recovery Time
Body Diode Reverse Recovery Charge I
F
=8A, dI/dt=500A/µs
10
22
ns
nC
A. The value of R
θJA
is measured with the device mounted on
FR-4 board with 2oz. Copper, in a still air environment with T
A
=25°C. The value
in any given application depends on the user's specific board design.
B. The power dissipation P
D
is based on T
J(MAX)
=150°C, using
≤
10s junction-to-ambient thermal resistance.
C. Repetitive rating, pulse width limited by junction temperature T
J(MAX)
=150°C. Ratings are based on low frequency and duty cycles to keep
initialT
J
=25°C.
D. The R
θJA
is the sum of the thermal impedence from junction to lead R
θJL
and lead to ambient.
E. The static characteristics in Figures 1 to 6 are obtained using <300µs pulses, duty cycle 0.5% max.
F. These curves are based on the junction-to-ambient thermal impedence which is measured with the device mounted on 1in
2
FR-4 board with 2oz.
Copper, assuming a maximum junction temperature of T
J(MAX)
=150°C. The SOA curve provides a single pulse rating.
THIS PRODUCT HAS BEEN DESIGNED AND QUALIFIED FOR THE CONSUMER MARKET. APPLICATIONS OR USES AS CRITICAL
COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS ARE NOT AUTHORIZED. AOS DOES NOT ASSUME ANY LIABILITY ARISING
OUT OF SUCH APPLICATIONS OR USES OF ITS PRODUCTS. AOS RESERVES THE RIGHT TO IMPROVE PRODUCT DESIGN,
FUNCTIONS AND RELIABILITY WITHOUT NOTICE.
Rev 3: Mar. 2011
www.aosmd.com
Page 5 of 8
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