Fairchild FDD8778, FDU8778 service manual

tm

FDD8778/FDU8778
N-Channel PowerTrench® MOSFET

25V, 35A, 14mΩ

FDD8778/FDU8778 N-Channel PowerTrench

May 2006

Features

 Max r

 Max r

 Low gate charge: Q

= 14.0mΩ at V

DS(on)

= 21.0mΩ at V

DS(on)

= 10V, ID = 35A

GS

= 4.5V, ID = 33A

GS

= 12.6nC(Typ), VGS = 10V

g(TOT)

General Description

This N-Channel MOSFET has been designed specifically
to improve the overall efficiency of DC/DC converters using
either synchronous or conventional switching PWM
controllers. It has been optimized for low gate charge, low
r

and fast switching speed.

DS(on)

 Low gate resistance

E

E

R

 RoHS compliant

F

I

D

A

E

L

M

P

L

E

M

E

N

T

A

T

I

O

N

Application

 DC-DC for Desktop Computers and Servers

 VRM for Intermediate Bus Architecture

G

G

MOSFET Maximum Ratings T

DS

I-PAK

(TO-251AA)

= 25°C unless otherwise noted

C

D

S

Short Lead I-PAK

G

Symbol Parameter Ratings Units

V

DS

V

GS

Drain to Source Voltage 25 V

Gate to Source Voltage ±20 V

Drain Current -Continuous (Package Limited) 35

I

D

-Pulsed (Note 1) 145

E

AS

P

D

, T

T

J

STG

Single Pulse Avalanche Energy (Note 2) 24 mJ

Power Dissipation 39 W

Operating and Storage Temperature -55 to 175 °C

Thermal Characteristics

D

®

MOSFET

S

A -Continuous (Die Limited) 40

R

θJC

R

θJA

R

θJA

Thermal Resistance, Junction to Case TO-252,TO-251 3.8 °C/W

Thermal Resistance, Junction to Ambient TO-252,TO-251 100 °C/W

Thermal Resistance, Junction to Ambient TO-252,1in2 copper pad area 52 °C/W

Package Marking and Ordering Information

Device Marking Device Package Reel Size Tape Width Quantity

FDD8778 FDD8778 TO-252AA 13’’ 12mm 2500 units

FDU8778 FDU8778 TO-251AA N/A(Tube) N/A 75 units

FDU8778 FDU8778_F071 TO-251AA N/A(Tube) N/A 75 units

©2006 Fairchild Semiconductor Corporation
FDD8778/FDU8778 Rev. A

www.fairchildsemi.com1

Electrical Characteristics T

= 25°C unless otherwise noted

J

Symbol Parameter Test Conditions Min Typ Max Units

Off Characteristics

BV

∆BV
∆T

I

DSS

I

GSS

DSS

DSS

J

Drain to Source Breakdown Voltage ID = 250µA, VGS = 0V 25 V

Breakdown Voltage Temperature
Coefficient

Zero Gate Voltage Drain Current

ID = 250µA, referenced to
25

°C

VDS = 20V,
V

GS

= 0V

TJ = 150°C 250

17.2 mV/°C

1

Gate to Source Leakage Current VGS = ±20V ±10 µA

FDD8778/FDU8778 N-Channel PowerTrench

µA

On Characteristics

V

GS(th)

∆V
∆T

r

DS(on)

GS(th)

J

Gate to Source Threshold Voltage VGS = VDS, ID = 250µA 1.2 1.5 2.5 V

Gate to Source Threshold Voltage
Temperature Coefficient

Drain to Source On Resistance

Dynamic Characteristics

C

iss

C

oss

C

rss

R

g

Input Capacitance

Output Capacitance 160 215 pF

Reverse Transfer Capacitance 108 162 pF

Gate Resistance f = 1MHz 1.3 Ω

Switching Characteristics

t

d(on)

t

r

t

d(off)

t

f

Q

g(TOT)

Q

g(5)

Q

gs

Q

gd

Turn-On Delay Time

Rise Time 22 35 ns

Turn-Off Delay Time 43 69 ns

Fall Time 32 51 ns

Total Gate Charge at 10V V

Total Gate Charge at 5V V

Gate to Source Gate Charge 2.1 nC

Gate to Drain “Miller”Charge 3.2 nC

Drain-Source Diode Characteristics

V

SD

t

rr

Q

rr

Notes:

1: Pulse time < 300µs, Duty cycle = 2%.
2: Starting T

Source to Drain Diode Forward Voltage

Reverse Recovery Time IF = 35A, di/dt = 100A/µs 25 38 ns

Reverse Recovery Charge IF = 35A, di/dt = 100A/µs 17 26 nC

= 25oC, L = 0.1mH, IAS = 22A ,VDD = 23V, VGS = 10V.

J

ID = 250µA, referenced to
25

°C

-5.3 mV/°C

VGS = 10V, ID = 35A 11. 6 14.0

VGS = 4.5V, ID = 33A 15.7 21.0

VGS = 10V, ID = 35A
TJ = 175°C

VDS = 13V, VGS = 0V,

18.2 23.8

635 845 pF

f = 1MHz

6 12 ns

VDD = 13V, ID = 35A
VGS = 10V, RGS = 27Ω

= 0V to 10V

GS

= 0V to 5V 6.7 9.4 nC

GS

V

= 0V, IS = 35A 1.03 1.25

GS

V

= 0V, IS = 15A 0.89 1.2

GS

VDD = 13V
I

= 35A

D

Ig = 1.0mA

12.6 18 nC

mΩ

®

MOSFET

V

FDD8778/FDU8778 Rev. A www.fairchildsemi.com2