Fairchild Semiconductor FDS9945 Datasheet

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FDS9945

FDS9945

60V N-Channel PowerTrench MOSFET

February 2001

General Description

These N Channel Logic Level MOSFET have been
designed specifically to improve the overall efficiency of
DC/DC converters using either synchronous or
conventional switching PWM controllers.

The MOSFET feature faster switching and lower gate
charge than other MOSFET with comparable RDS(on)

specifications.
The result is a MOSFET that is easy and safer to drive

(even at very high frequencies), and DC/DC power
supply designs with higher overall efficiency.

D1

D

D1

D

D2

D

D2

D

S2

S

G2

S

G1

S1

S

o

=25

C unless otherwise noted

A

SO-8

SO-8

Pin 1

Absolute Maximum Ratings T

Features

• 3.5 A, 60 V. R
R

• Optimized for use in switching DC/DC converters
with PWM controllers

• Very fast switching

• Low gate charge.

5
6
7
8

= 0.100Ω @ VGS = 10 V

DS(ON)

= 0.200Ω @ VGS = 4.5V

DS(ON)

4

Q1

Q2

3
2
1

Symbol Parameter Ratings Units

V

Drain-Source Voltage 60 V

DSS

V

Gate-Source Voltage ±20 V

GSS

ID Drain Current – Continuous (Note 1a) 3.5 A
– Pulsed 10
PD

TJ, T

STG

Power Dissipation for Single Operation (Note 1a) 2
(Note 1b)
(Note 1c)

Operating and Storage Junction Temperature Range -55 to +175 °C

1.6

1.0

W

Thermal Characteristics

R

Thermal Resistance, Junction-to-Ambient (Note 1a) 78 (steady state), 50 (10 sec) °C/W

θJA

R

Thermal Resistance, Junction-to-Ambient (Note 1c) 135 °C/W

θJA

R

Thermal Resistance, Junction-to-Case (Note 1) 40 °C/W

θJC

Package Marking and Ordering Information

Device Marking Device Reel Size Tape width Quantity

FDS9945 FDS9945 13’’ 12mm 2500 units

2001 Fairchild Semiconductor Corporation FDS9945 Rev B(W)

FDS9945

Electrical Characteristics T

Symbol

Parameter Test Conditions Min Typ Max Units

= 25°C unless otherwise noted

A

Off Characteristics

BV

Drain–Source Breakdown Voltage VGS = 0 V, ID = 250 µA 60 V

DSS

∆BVDSS
∆TJ

I

Zero Gate Voltage Drain Current VDS = 48 V, VGS = 0 V 1 µA

DSS

I

GSSF

I

GSSR

Breakdown Voltage Temperature
Coefficient

ID = 250 µA, Referenced to 25°C 62.5 mV/°C

Gate–Body Leakage, Forward VGS = 20 V, VDS = 0 V 100 nA

Gate–Body Leakage, Reverse VGS = –20 V VDS = 0 V –100 nA

On Characteristics (Note 2)

V

Gate Threshold Voltage VDS = VGS, ID = 250 µA 1 2.5 3 V

GS(th)

∆VGS(th)
∆TJ

R

DS(on)

I

D(on)

Gate Threshold Voltage
Temperature Coefficient

Static Drain–Source

On–Resistance

ID = 250 µA, Referenced to 25°C
VGS = 10 V, ID = 3.5 A

VGS = 4.5V, ID = 2.5 A
VGS= 10 V, ID =3.5A, TJ=125°C

–6 mV/°C

74
103
126

100
200
170

m Ω

On–State Drain Current VGS = 10 V, = VDS =30 V 10 A

gFS Forward Transconductance VDS = 5V, ID = 3.5 A 8.6 S

Dynamic Characteristics

C

Input Capacitance 420 pF

iss

C

Output Capacitance 48 pF

oss

C

Reverse Transfer Capacitance

rss

VDS = 30 V, V
f = 1.0 MHz

= 0 V,

GS

20 pF

Switching Characteristics (Note 2)

t

Turn–On Delay Time 7 14 ns

d(on)

tr Turn–On Rise Time 4.3 8.6 ns
t

Turn–Off Delay Time 19 34 ns

d(off)

tf Turn–Off Fall Time
Qg Total Gate Charge 8 13 nC
Qgs Gate–Source Charge 4 nC
Qgd Gate–Drain Charge

VDD = 30 V, ID = 1 A,
VGS = 10 V, R

GEN

= 6 Ω

VDS = 30 V, ID = 3.5 A,
VGS = 5 V

3 6 ns

2.5 nC

Drain–Source Diode Characteristics and Maximum Ratings

IS Maximum Continuous Drain–Source Diode Forward Current 2.1 A
VSD

Notes:

1. R

θJA

the drain pins. R

Scale 1 : 1 on letter size paper

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

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

a) 78°/W when

mounted on a 0.5in2
pad of 2 oz copper

is determined by the user's board design.

θCA

VGS = 0 V, IS = 2.1 A (Note 2) 0.8 1.2 V

b) 125°/W when

mounted on a 0.02
in2 pad of 2 oz
copper

c) 135°/W when mounted on a

minimum pad.

FDS9945 Rev B(W)