Alpha & Omega Semiconductor AO4918 Service Manual

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AO4918
Asymmetric Dual N-Channel Enhancement Mode Field Effect
Transistor

General Description

Features
Q1 Q2

The AO4918 uses advanced trench technology to provid
excellent R

and low gate charge. The two

DS(ON)

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 furthe

Standard Product AO4918 is Pb-free (meets ROHS &
Sony 259 specifications). AO4918L is a Green Product
ordering option. AO4918 and AO4918L are electrically
identical.

1

8
7
6
5

G2
D1/S2/K
D1/S2
D1/S2/K

S1/A

D2
D2

G1

2
3
4

SOIC-8

Absolute Maximum Ratings T

=25°C unless otherwise noted

A

Parameter

Drain-Source Voltage
Gate-Source Voltage ±20

Continuous Drain
Current

A

Pulsed Drain Current

Power Dissipation

B

T

A

T

A

T

A

T

A

=25°C
=70°C

=25°C
=70°C

VDS (V) = 30V VDS(V) = 30V

= 9.3A (VGS = 10V) ID=8.3A (VGS = 10V

I

D

R
R

< 14.5mΩ <18mΩ (VGS = 10V)

DS(ON)

< 16mΩ <27mΩ (VGS = 4.5V)

DS(ON)

SCHOTTKY

V

(V) = 30V, IF = 3A, VF<0.5V@1A

DS

D1

Q1

K

G1

Symbol Max Q

V

DS

V

GS

A

S1

Max Q1

Q2

G2

30

±12

9.3

I

D

I

DM

P

D

TJ, T

STG

7.4
40 40

2

1.28 1.28

-55 to 150 -55 to 150Junction and Storage Temperature Range

D2

S2

30

8.3

6.7

2

Unit

V
V

A

W
°C

Parameter

Reverse Voltage
Continuous Forward
Current

A

Pulsed Diode Forward Current

T

A

T

A

=25°C
=70°C

B

TA=25°C

Power Dissipation

A

T

=70°C

A

Junction and Storage Temperature Range

Symbol

V

DS

I

F

I

FM

P

D

TJ, T

STG

Maximum Schottky

30 V

3

2.2
20

2

1.28

-55 to 150 °C

Units

A

W

Alpha & Omega Semiconductor, Ltd.

AO4918

Parameter: Thermal Characteristics MOSFET Q1

Maximum Junction-to-Ambient
Maximum Junction-to-Ambient
Maximum Junction-to-Lead

Parameter: Thermal Characteristics MOSFET Q2 Typ Max

Maximum Junction-to-Ambient
Maximum Junction-to-Ambient
Maximum Junction-to-Lead

Thermal Characteristics Schottky

Maximum Junction-to-Ambient
Maximum Junction-to-Lead

A: The value of R
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

θJA

D. The static characteristics in Figures 1 to 6 are obtained using 80 µs pulses, duty cycle 0.5% max.

E. These tests are performed with the device mounted on 1 in
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

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.

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

θJA

is the sum of the thermal impedence from junction to lead R

A

A

C

A

A

C

A

A

C

t ≤ 10s
Steady-State
Steady-State

t ≤ 10s
Steady-State
Steady-State

t ≤ 10s
Steady-State
Steady-State

2

Symbol Units

R

θJA

R

θJL

Symbol Units

R

θJA

R

θJL

R

θJA

R

θJL

and lead to ambient.

θJL

FR-4 board with 2oz. Copper, in a still air environment with T A=25°C. The

Typ

53

81.9

30.5

53

81.9 110

30.5 40

50.4
86

26.6

Max

62.5
110

40

62.5

62.5Maximum Junction-to-Ambient
110

40

°C/W

°C/W

°C/W

Alpha Omega Semiconductor, Ltd.

AO4918

Q1 Electrical Characteristics (T

Symbol Min Typ Max Units

=25°C unless otherwise noted)

J

Parameter Conditions

STATIC PARAMETERS

BV

I

DSS

I

GSS

V

I

D(ON)

R

g

FS

V

I

S

GS(th)

DS(ON)

SD

Drain-Source Breakdown Voltage I

DSS

Zero Gate Voltage Drain Current.
(Set by Schottky leakage)

Gate-Body leakage current V

Gate Threshold Voltage V

On state drain current V

Static Drain-Source On-Resistance

Forward Transconductance V

Diode+Schottky Forward Voltage I
Maximum Body-Diode+Schottky Continuous Current

=250µA, VGS=0V

D

V

=30V

R

=30V, TJ=125°C

V

R

V

=30V, TJ=150°C

R

=0V, VGS= ±12V

DS

DS=VGS ID

GS

V

GS

V

GS

DS

=1A

S

=250µA

=4.5V, VDS=5V

=10V, ID=9.3A

=4.5V, ID=8.8A

=5V, ID=9.3A

T

=125°C

J

30 V

0.007 0.05

3.2 10

mA

12 20

100 nA

0.6 1.1 2 V

40 A

11.7 14.5

15.4 19

13.1 16

mΩ

m

30 37 S

0.46 0.5 V

3.5 A

Ω

DYNAMIC PARAMETERS

C

iss

C

oss

C

rss

R

g

Input Capacitance

Output Capacitance (FET + Schottky)

Reverse Transfer Capacitance

Gate resistance V

=0V, VDS=15V, f=1MHz

V

GS

=0V, VDS=0V, f=1MHz

GS

3740 4488 pF

295 pF

186 pF

0.86 1.1 Ω

SWITCHING PARAMETERS

Q

g

Q

gs

Q

gd

t

D(on)

t

r

t

D(off)

t

f

t

rr

Q

rr

A: The value of R
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
D. The static characteristics in Figures 1 to 6,12,14 are obtained using 80 µs pulses, duty cycle 0.5% max.

E. These tests are performed with the device mounted on 1 in
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.

Total Gate Charge

Gate Source Charge

Gate Drain Charge

Turn-On DelayTime

Turn-On Rise Time

Turn-Off DelayTime

Turn-Off Fall Time

Body Diode + Schottky Reverse Recovery Time

Body Diode + Schottky Reverse Recovery Charge

is measured with the device mounted on 1in 2 FR-4 board with 2oz. Copper, in a still air environment with T

θJA

is the sum of the thermal impedence from junction to lead R

θJA

2

FR-4 board with 2oz. Copper, in a still air environment with T A=25°C. The SOA curve

=4.5V, VDS=15V, ID=9.3A

V

GS

V

=10V, VDS=15V, RL=1.6Ω,

GS

=3Ω

R

GEN

=9.3A, dI/dt=100A/µs

I

F

=9.3A, dI/dt=100A/µs

I

F

and lead to ambient.

θJL

30.5 37 nC

4.5 nC

8.5 nC

69ns

8.2 12 ns

54.5 75 ns

10.5 15 ns

28 ns

23.5

16 nC

13.3

=25°C. The value in any

A

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.

Alpha Omega Semiconductor, Ltd.