SG5841 Datasheet, PDF (1/14 Pages) Fairchild Semiconductor – Highly Integrated Green-Mode PWM Controller

Highly Integrated Green-Mode PWM Controller
Product Specification
SG5841/J
FEATURES
„ Green-Mode PWM Controller
„ Low Start-Up Current (14µA)
„ Low Operating Current (4mA)
„ Programmable PWM Frequency with Hopping
„ Peak-Current-Mode Control
„ Cycle-by-Cycle Current Limiting
„ Synchronized Slope Compensation
„ Leading-Edge Blanking
„ Constant Output Power Limit
„ Totem Pole Output with Soft Driving
„ V_DD Over-Voltage Clamping
„ Programmable Over-Temperature Protection (OTP)
„ Internal Open-Loop Protection
„ V_DD Under-Voltage Lockout (UVLO)
„ GATE Output Maximum Voltage Clamp (18V)
APPLICATIONS
General-purpose switch-mode power supplies and
flyback power converters, including:
„ Power Adapters
„ Open-Frame SMPS
DESCRIPTION
The highly integrated SG5841/J series of PWM
controllers provides several features to enhance the
performance of flyback converters.
To minimize standby power consumption, a proprietary
green-mode function provides off-time modulation to
continuously decrease the switching frequency at
light-load conditions. This green-mode function enables
the power supply to meet international power
conservation requirements. To further reduce power
consumption, SG5841/J is manufactured using the
BiCMOS process. This allows a low start-up current,
around 14µA, and an operating current of only 4mA. As a
result, a large start-up resistance can be used.
The SG5841/J built-in synchronized slope compensation
achieves stable peak-current-mode control. The
proprietary internal sawtooth power-limiter ensures
constant output power limit over a wide range of AC input
voltages, from 90VAC to 264VAC.
SG5841/J provides many protection functions. In addition
to cycle-by-cycle current limiting, the internal open-loop
protection circuit ensures safety should an open-loop or
output-short-circuit failure occur. PWM output is disabled
until V_DD drops below the UVLO lower limit, then the
controller starts again. An external NTC thermistor can be
applied for over-temperature protection.
SG5841/J is available in an 8-pin DIP or SOP package.
TYPICAL APPLICATION
SG5841/J
© System General Corp.
Version 1.3.1 (IAO33.0017.B6)
-1-
www.sg.com.tw • www.fairchildsemi.com
September 20, 2007