FAN7556 Datasheet, PDF (1/10 Pages) Fairchild Semiconductor – Voltage Mode PWM Controller

FAN7556
Voltage Mode PWM Controller
www.fairchildsemi.com
Features
• Voltage Mode Control
• Pulse by Pulse Current Limiting
• Low External Components
• Under Voltage Lockout ( UVLO): 9V/15V
• Stand-by Current: Typ. 100uA
• Power Saving Mode Current: Typ. 200uA
• Operating Current: Typ. 7mA
• Soft Start
• On/off Control
• Over Load Protection (OLP)
• Over Current Protection (OCP)
• Over Voltage Protection (OVP)
• Wide Operating Frequency Range (20kHz ~ 500kHz)
• Auto-Restart Function
Applications
• Off-Line & DC-DC Converter
Description
The FAN7556 is a fixed frequency voltage mode PWM
controller. It is specially designed for off-line and DC-DC
converter applications with minimal external components.
These integrated circuits feature a trimmed oscillator for
precise duty cycle control, a temperature compensated
reference, an on/off control, a high gain error amplifier, a
current sensing comparator, and a high current totem-pole
output. The FAN7556 has various protection functions such
as an over load protection (OLP), an over current
protection(OCP), and an over voltage protection(OVP). The
FAN7556 is available in the 8DIP package as well as the
8SOP package.
8-DIP
1
8-SOP
1
Internal Block Diagram
LA 1
2V
COM
3.5V
Vref
S/S 8
100uA
CT
74
SR
Q
off
PWR
/
Vref
on ^SAVE
OVP
UVLO
Vcc
6
34V
15/9V
0.3V
1k _1.5V
OSC
PWM
CLK
14V
5 OUT
FB 2
1mA
3k
Vref
Vcc
5uA
OLP
6V
COM-out
OVP-out
2.7V
UVLO-out
QR
S
S
Q
R
OCP
3 IS
0.25V
4 GND
©2002 Fairchild Semiconductor Corporation
Rev. 1.0.1