[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.