SG6858_09 Datasheet, PDF (1/13 Pages) Fairchild Semiconductor – Low-Cost, Green-Mode, PWM Controller for Flyback Converters

September 2009
SG6858
Low-Cost, Green-Mode, PWM Controller for Flyback
Converters
Features
ƒ Green-Mode PWM
ƒ Supports the ”Blue Angel” Standard
ƒ Low Startup Current: 10µA (Maximum)
ƒ Low Operating Current: 2.5mA
ƒ Leading-Edge Blanking (LEB)
ƒ Constant Output Power Limit
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
ƒ VDD Over-Voltage Protection with Auto-Restart
ƒ Gate Output Voltage Clamped at 17V
ƒ Few External Components Required
ƒ SSOT-26 and DIP-8 Packages Available
Applications
ƒ Battery chargers for cellular phones, cordless
phones, PDAs, digital cameras, and power tools
ƒ Power adapters for ink jet printers, video game
consoles, and portable audio players
ƒ Open-frame SMPS for TV/DVD standby and other
auxiliary supplies, home appliances, PC 5V
standby power, and consumer electronics
ƒ Replacements for linear transformers and RCC
SMPS
ƒ Offline High Brightness (HB) LED drivers
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
startup current to 10µA and the operating current to
2.5mA. To further improve power conservation, a large
startup 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 circuits.
To protect the external power MOSFET from being
damaged by supply over voltage, the output driver is
clamped at 17V. SG6858 controllers can improve the
performance and reduce the production cost of power
supplies. The SG6858 replaces linear and RCC-mode
power adapters. It is available in 8-pin DIP and 6-pin
SSOT-26 packages.
Ordering Information
Part Number
SG6858TZ
SG6858DZ
Operating Temperature Range
-40 to +125°C
-40 to +125°C
Eco Status ^{Package Packing Method}
RoHS
6-Pin SSOT-26 Tape & Reel
RoHS
8-Pin DIP-8
Tube
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
© 2008 Fairchild Semiconductor Corporation
SG6858 • Rev. 1.2.4
www.fairchildsemi.com