Service manual

©2003 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev.1.0.1
Features
• Precision Fixed Operating Frequency
• FS7M0880(66kHz)
• Pulse By Pulse Over Current Limiting
• Over Load Protection
• Over Voltage Protection (Min. 25V)
• Internal Thermal Shutdown Function
• Under Voltage Lockout
• Internal High Voltage Sense FET
• Latch Up Mode
•Soft Start
Description
The Fairchild Power Switch(FPS) product family is specially
designed for an off line SMPS with minimal external
components. The Fairchild Power Switch(FPS) consists of a
high voltage power SenseFET and the current mode PWM con-
troller IC. The PWM controller includes an integrated fixed
oscillator, the under voltage lock out, the leading edge blanking
block, the optimized gate turn-on/turn-off driver, the thermal
shut down protection, the over voltage protection, the tempera-
ture compensated precision current sources for loop compensa-
tion and an fault protection circuit. Compared to just PWM
controller combined MosFET or R
CC
switching converter solu-
tion, a Fairchild Power Switch(FPS) can reduce total compo-
nent price, design size, and weight,also simultaneously increase
efficiency, productivity, and system reliability. It has a simple
method of application well suited for cost down design in either
a flyback converter or a forward converter.
TO-3P-5L
1. DRAIN 2. GND 3. V
CC
4. FB 5. S/S
1
Internal Block Diagram
Sense
#4
Feedback
LEB
#5
Soft Start
Rsense
2.5R
R
OSC
Reset
1mA5uA
Vck
R
S
Q
7.5V
5V
R
S
Q
Voffset
#3 Vcc
Voltage
Ref.
Control IC
SenseFET
#4
Drain
#2
Source
GND
Vcc Vcc
Reset
Thermal
Protection
UVLO
Good
Logic
OVP
OCL
Sense
#4
Feedback
LEB
#5
Soft Start
Rsense
2.5R
R
OSC
Reset
1mA5uA
Vck
R
S
Q
7.5V
5V
R
S
Q
Voffset
#3 Vcc
Voltage
Ref.
Control IC
SenseFET
#4
Drain
#2
Source
GND
Vcc Vcc
Reset
Thermal
Protection
UVLO
Good
Logic
OVP
OCL
FS7M0880
Fairchild Power Switch(FPS)
94