Symbol
Max Q2
Units
V
DS
V
V
GS
V
I
DM
T
J
, T
STG
C
Symbol
V
DS
I
FM
T
J
, T
STG
Gate-Source Voltage
20
30
Absolute Maximum Ratings T
A
=25C unless otherwise noted
Parameter
Drain-Source Voltage
W
-55 to 150
-55 to 150
Junction and Storage Temperature Range
2
1.28
1.28
T
A
=25C
T
A
=70C
2
A
6.7
40
40
8.3
7.4
T
A
=25C
T
A
=70C
Power Dissipation
P
D
Pulsed Drain Current
B
Continuous Drain
Current
A
I
D
Maximum Schottky
Max Q1
30
12
9.3
Units
30
V
T
A
=25C
Parameter
Reverse Voltage
A
2.2
20
3
T
A
=70C
Pulsed Diode Forward Current
B
Continuous Forward
Current
A
P
D
I
F
T
A
=25C
T
A
=70C
Junction and Storage Temperature Range
Power Dissipation
A
W
1.28
-55 to 150
C
2
AO4918
Asymmetric Dual N-Channel Enhancement Mode Field Effect
Transistor
Features
Q1 Q2
V
DS
(V) = 30V V
DS
(V) = 30V
I
D
= 9.3A (V
GS
= 10V) I
D
=8.3A (V
GS
= 10V
R
DS(ON)
< 14.5m
<18m
(V
GS
= 10V)
R
DS(ON)
< 16m
<27m
(V
GS
= 4.5V)
SCHOTTKY
V
DS
(V) = 30V, I
F
= 3A, V
F
<0.5V@1A
General Description
The AO4918 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 Schottky diode is co-packaged in parallel
with the synchronous MOSFET to boost efficiency further
Standard Product AO4918 is Pb-free (meets ROHS &
Sony 259 specifications). AO4918L is a Green Product
ordering option. AO4918 and AO4918L are electrically
identical.
SOIC-8
G1
S1/A
D2
D2
D1/S2/K
D1/S2/K
D1/S2/K
G2
1
2
3
4
8
7
6
5
G1
D1
S1
K
A
G2
D2
S2
Q1
Q2
Alpha & Omega Semiconductor, Ltd.
AO491
8
Symbol
Units
R
JL
Symbol
Units
R
JL
R
JL
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.
Maximum Junction-to-Lead
C
Steady-State
86
26.6
50.4
R
JA
62.5
Maximum Junction-to-Ambient
A
t 10s
R
JA
Maximum Junction-to-Ambient
A
Steady-State
110
110
Maximum Junction-to-Lead
C
Steady-State
30.5
Typ
Maximum Junction-to-Ambient
A
Steady-State
Parameter: Thermal Characteristics MOSFET Q1
Maximum Junction-to-Ambient
A
t 10s
40
Thermal Characteristics Schottky
62.5
40
53
81.9
62.5
C/W
Maximum Junction-to-Ambient
A
Steady-State
Max
C/W
C/W
Parameter: Thermal Characteristics MOSFET Q2
Typ
Max
Maximum Junction-to-Ambient
A
t 10s
R
JA
53
81.9
110
Maximum Junction-to-Lead
C
Steady-State
30.5
40
A: The value of R
JA
is measured with the device mounted on 1in
2
FR-4 board with 2oz. Copper, in a still air environment with T
A
=25C. The
value in any given application depends on the user's specific board design. The current rating is based on the t 10s thermal resistance
rating.
B: Repetitive rating, pulse width limited by junction temperature.
C. The R
JA
is the sum of the thermal impedence from junction to lead R
JL
and lead to ambient.
D. The static characteristics in Figures 1 to 6 are obtained using 80
s pulses, duty cycle 0.5% max.
E. These tests are performed with the device mounted on 1 in
2
FR-4 board with 2oz. Copper, in a still air environment with T
A
=25C. The
SOA curve provides a single pulse rating.
F. The Schottky appears in parallel with the MOSFET body diode, even though it is a separate chip. Therefore, we provide the net forward
drop, capacitance and recovery characteristics of the MOSFET and Schottky. However, the thermal resistance is specified for each chip
separately.
Rev4: August 2005
Alpha Omega Semiconductor, Ltd.
AO4918
Symbol
Min
Typ
Max Units
BV
DSS
30
V
0.007 0.05
3.2
10
12
20
I
GSS
100
nA
V
GS(th)
0.6
1.1
2
V
I
D(ON)
40
A
11.7
14.5
T
J
=125C
15.4
19
13.1
16
m
g
FS
30
37
S
V
SD
0.46
0.5
V
I
S
3.5
A
C
iss
3740 4488
pF
C
oss
295
pF
C
rss
186
pF
R
g
0.86
1.1
Q
g
30.5
37
nC
Q
gs
4.5
nC
Q
gd
8.5
nC
t
D(on)
6
9
ns
t
r
8.2
12
ns
t
D(off)
54.5
75
ns
t
f
10.5
15
ns
t
rr
Body Diode + Schottky Reverse Recovery Time
I
F
=9.3A, dI/dt=100A/
s
23.5
28
ns
Q
rr
Body Diode + Schottky Reverse Recovery Charge
I
F
=9.3A, dI/dt=100A/
s
13.3
16
nC
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.
Gate Source Charge
Gate Drain Charge
Turn-On DelayTime
V
GS
=10V, V
DS
=15V, R
L
=1.6
,
R
GEN
=3
V
GS
=4.5V, V
DS
=15V, I
D
=9.3A
Turn-On Rise Time
Turn-Off DelayTime
Turn-Off Fall Time
SWITCHING PARAMETERS
Total Gate Charge
Gate resistance
V
GS
=0V, V
DS
=0V, f=1MHz
Forward Transconductance
V
DS
=5V, I
D
=9.3A
Diode+Schottky Forward Voltage
I
S
=1A
Maximum Body-Diode+Schottky Continuous Current
DYNAMIC PARAMETERS
Input Capacitance
V
GS
=0V, V
DS
=15V, f=1MHz
Output Capacitance (FET + Schottky)
Reverse Transfer Capacitance
R
DS(ON)
Static Drain-Source On-Resistance
V
GS
=10V, I
D
=9.3A
m
V
GS
=4.5V, I
D
=8.8A
Gate Threshold Voltage
V
DS
=V
GS
I
D
=250
A
On state drain current
V
GS
=4.5V, V
DS
=5V
mA
Gate-Body leakage current
V
DS
=0V, V
GS
= 12V
V
R
=30V, T
J
=125C
V
R
=30V, T
J
=150C
Drain-Source Breakdown Voltage
I
D
=250
A, V
GS
=0V
I
DSS
Zero Gate Voltage Drain Current.
(Set by Schottky leakage)
V
R
=30V
Q1 Electrical Characteristics (T
J
=25C unless otherwise noted)
Parameter
Conditions
STATIC PARAMETERS
A: The value of R
JA
is measured with the device mounted on 1in
2
FR-4 board with 2oz. Copper, in a still air environment with T
A
=25C. The value in any
given application depends on the user's specific board design. The current rating is based on the t 10s thermal resistance rating.
B: Repetitive rating, pulse width limited by junction temperature.
C. The R
JA
is the sum of the thermal impedence from junction to lead R
JL
and lead to ambient.
D. The static characteristics in Figures 1 to 6,12,14 are obtained using 80
s pulses, duty cycle 0.5% max.
E. These tests are performed with the device mounted on 1 in
2
FR-4 board with 2oz. Copper, in a still air environment with T
A
=25C. The SOA curve
provides a single pulse rating.
F. The Schottky appears in parallel with the MOSFET body diode, even though it is a separate chip. Therefore, we provide the net forward drop, capacitance
and recovery characteristics of the MOSFET and Schottky. However, the thermal resistance is specified for each chip separately
Rev4: August 2005
.
Alpha Omega Semiconductor, Ltd.
AO4918
Q1 TYPICAL ELECTRICAL AND THERMAL CHARACTERISTICS
0
10
20
30
40
0
1
2
3
4
5
V
DS
(Volts)
Fig 1: On-Region Characteristics
I
D
(A)
V
GS
=2V
2.5V
4.5V
10V
0
5
10
15
20
25
30
0.5
1
1.5
2
2.5
V
GS
(Volts)
Figure 2: Transfer Characteristics
I
D
(A)
10
11
12
13
14
0
5
10
15
20
25
30
I
D
(A)
Figure 3: On-Resistance vs. Drain Current and
Gate Voltage
R
DS(ON)
(m
)
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
0.0
0.2
0.4
0.6
0.8
1.0
V
SD
(Volts)
Figure 6: Body-Diode Characteristics
(Note F)
I
S
(A)
125C
FET+SCHOTTKY
0.8
1
1.2
1.4
1.6
1.8
0
50
100
150
200
Temperature (C)
Figure 4: On resistance vs. Junction Temperature
Norm
al
i
z
ed On-Resi
stance
V
GS
=10V
V
GS
=4.5V
5
10
15
20
25
30
0
2
4
6
8
10
V
GS
(Volts)
Figure 5: On resistance vs. Gate-Source Voltage
R
DS(ON)
(m
)
V
DS
=5V
V
GS
=4.5V
V
GS
=10V
I
D
=9.3A
25C
I
D
=9.3A
125C
25C
25C
125C
Alpha Omega Semiconductor, Ltd.
AO4918
Q1 TYPICAL ELECTRICAL AND THERMAL CHARACTERISTICS
0
1
2
3
4
5
0
5
10
15
20
25
30
35
Q
g
(nC)
Figure 7: Gate-Charge Characteristics
V
GS
(V
o
l
ts)
100
1000
10000
0
5
10
15
20
25
30
V
DS
(Volts)
Figure 8: Capacitance Characteristics
Capaci
tance (pF)
C
iss
C
oss
FET+SCHOTTKY
0
10
20
30
40
0.001
0.01
0.1
1
10
100
1000
Pulse Width (s)
Figure 10: Single Pulse Power Rating Junction-to-
Ambient (Note E)
Po
w
e
r
(
W
)
0.01
0.1
1
10
0.00001
0.0001
0.001
0.01
0.1
1
10
100
1000
Pulse Width (s)
Figure 11: Normalized Maximum Transient Thermal Impedance
Z
JA
Norm
al
i
z
ed Transi
ent
Therm
al
Resi
stance
C
rss
0.1
1.0
10.0
100.0
0.1
1
10
100
V
DS
(Volts)
I
D
(A)
Figure 9: Maximum Forward Biased Safe
Operating Area (Note E)
100
s
10ms
1ms
0.1s
1s
10s
DC
R
DS(ON)
limited
10
s
V
DS
=15V
I
D
=9.3A
Single Pulse
D=T
on
/T
T
J,PK
=T
A
+P
DM
.Z
JA
.R
JA
R
JA
=62.5C/W
T
on
T
P
D
In descending order
D=0.5, 0.3, 0.1, 0.05, 0.02, 0.01, single pulse
T
J(Max)
=150C
T
A
=25C
f=1MHz
V
GS
=0V
T
J(Max)
=150C, T
A
=25C
Alpha Omega Semiconductor, Ltd.
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