[System General Corp.]

DESCRIPTION

The highly integrated SG6846 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 under light-load conditions. Under zero-load conditions, the power supply enters burst-mode. This completely shuts off PWM output. The output restarts just before the supply voltage drops below the UVLO lower limit. This green-mode function enables power supplies to easily meet international power conservation requirements.

FEATURES

■ Two-level OCP with 96mS delay time

■ Peak-current-mode operation with cycle-by-cycle current limiting

■ PWM frequency continuously decreasing w/ burst mode at light loads

■ Low start-up current (8uA)

■ Low operating current (3.7mA)

■ VDD over-voltage protection (OVP)

■ AC input brownout protection with hysteresis

■ Programmable over-temperature protection (OTP)

■ Constant power limit over universal AC input range

■ Internal latch circuit for OTP, OVP, OCP

■ Very few external components

APPLICATIONS

General-purpose switch mode power supplies and flyback power converters, including:

■ Power adapters

■ Open-frame SMPS

■ Specifically fit for SMPS with surge-current output, such as for printers, scanners, motor drivers, etc.