SG5851 Datasheet, PDF (1/11 Pages) Fairchild Semiconductor – Low-Cost Green-Mode PWM Controller for Flyback Converters

February 2008
SG5851
Low-Cost Green-Mode PWM Controller for Flyback
Converters
Features
ƒ Green-Mode PWM
ƒ Supports the “Blue Angel” Standard
ƒ Low Start-up Current: 9µA
ƒ Low Operating Current: 3mA
ƒ Leading-Edge Blanking
ƒ Constant Output Power Limit
ƒ Universal Input
ƒ Built-in Synchronized Slope Compensation
ƒ Current Mode Operation
ƒ Cycle-by-cycle Current Limiting
ƒ Under-Voltage Lockout (UVLO)
ƒ Programmable PWM Frequency with Frequency
Hopping
ƒ VDD Over-Voltage Protection (Auto Restart)
ƒ Gate Output Voltage Clamped at 17V
ƒ Low Cost
ƒ Few External Components Required
Applications
ƒ Power Adaptors
ƒ Open-Frame SMPS
Description
This highly integrated PWM controller provides several
special enhancements designed to meet the low
standby-power needs of low-power SMPS. To minimize
standby power consumption, the proprietary green-
mode function provides off-time modulation to linearly
decrease the switching frequency under light-load
conditions. This green-mode function enables the
power supply to meet even the strictest power
conservation requirements.
The BiCMOS fabrication process enables reducing the
start-up current to 9µA and the operating current to
3mA. To further improve power conservation, a large
start-up resistance can be used. Built-in synchronized
slope compensation ensures the stability of peak
current mode control. Proprietary internal compensation
provides a constant output power limit over a universal
AC input range (90VAC to 264VAC). Pulse-by-pulse
current limiting ensures safe operation even during
short-circuit conditions.
To protect the external power MOSFET from being
damaged by supply over voltage, the output driver is
clamped at 17V. SG5851 controllers, available in an
SOP package, can be used to improve the performance
and reduce the production cost of power supplies.
Ordering Information
Part Number
SG5851SZ
SG5851DZ
Operating Temperature Range
Package
Packing Method
-40°C to +85°C
8-pin Small Outline Package (SOP) Tape & Reel
-40°C to +85°C
8-pin Dual in-line Package (DIP)
Rail
All packages are lead free per JEDEC: J-STD-020B standard.
© 2007 Fairchild Semiconductor Corporation
SG5851 • Rev. 1.0.0
www.fairchildsemi.com