SG6901A Datasheet, PDF (1/18 Pages) Fairchild Semiconductor – PFC / Flyback PWM Controller

PFC / Flyback PWM Controller
FEATURES OVERVIEW
„ Interleaved PFC/PWM switching
„ Low start-up and operating current
„ Innovative switching charge multiplier-divider
„ Multi-vector control for improved PFC output
transient response
„ Average-current-mode control for PFC
„ Programmable two-level PFC output voltage
„ PFC over-voltage and under-voltage protections
„ PFC and PWM feedback open-loop protection
„ Cycle-by-cycle current limiting for PFC/PWM
„ Slope compensation for PWM
„ Constant power limit for PWM
„ Brownout protection
„ Over-temperature protection (OTP)
APPLICATIONS
„ Switching Power Supplies with Active PFC and
Standby Power
„ High-Power Adaptors
DESCRIPTION
The highly integrated SG6901A is designed for power
supplies with boost PFC and flyback PWM. It requires
Product Specification
SG6901A
very few external components to achieve versatile
protections. It is available in a 20-pin SOP package.
The patented interleave-switching feature synchronizes
the PFC and PWM stages and reduces switching noise.
For PFC stage, the proprietary multi-vector control
scheme provides a fast transient response in a
low-bandwidth PFC loop, in which the overshoot and
undershoot of the PFC voltage are clamped. If the
feedback loop is broken, the SG6901A shuts off PFC to
prevent extra-high voltage on output. Programmable
two-level output voltage control reduces the PFC output
voltage at low line input to increase the efficiency of the
power supply.
For the flyback PWM, the synchronized slope
compensation ensures the stability of the current loop
under continuous-conduction-mode operation. Built-in
line-voltage compensation maintains constant
output-power limit. Hiccup operation during output
overloading is also guaranteed.
In addition, SG6901A provides protection functions, such
as brownout and RI pin open/short protection.
Typical Application
© System General Corp.
Version 1.0.1 (IAO33.0062.B0)
-1-
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007