SG6859A Datasheet, PDF (1/12 Pages) Fairchild Semiconductor – Low-Cost, Green-Mode PWM Controller for Flyback Converters

March 2008
SG6859A
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
ƒ Small SOT-26 Package
Description
This highly integrated PWM controller provides several
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 during short-circuits.
To protect the external power MOSFET from damage by
supply over voltage, the SG6859A’s output driver is
clamped at 17V. SG6859A controllers can be used to
improve the performance and reduce the production
cost of power supplies. The best choice for replacing
linear and RCC-mode power adapters, the SG6859A is
available in 8-pin DIP and 6-pin SOT-26 packages.
Applications
General-purpose switching mode power supplies and
flyback power converters, such as:
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 auxiliary
supplies, home appliances, and consumer electronics
ƒ Replacements for linear transformers and RCC SMPS
ƒ PC 5V standby power
Ordering Information
Part Number
Operating Temperature Range
SG6859ATZ
SG6859ADZ
-20°C to +85°C
-20°C to +85°C
All packages are lead free per JEDEC: J-STD-020B standard.
© 2007 Fairchild Semiconductor Corporation
SG6859A Rev. 1.0.0
Package
SOT-26
DIP-8
Packing Method
Tape & reel
Tube
www.fairchildsemi.com