VIPER22ASTR-E

The VIPER22ASTR-E from STMicroelectronics is an integrated off-line converter combining a current-mode PWM controller and a 730V power MOSFET on a single chip. Operating at a fixed 60kHz frequency, it delivers up to 7W (wide range 85-265VAC) or 12W (European 195-265VAC) in the SO-8 package. The device features a wide VDD range (9-38V) accommodating auxiliary supply variations, automatic burst mode for light-load efficiency, and comprehensive protection including overtemperature, overcurrent, and overvoltage with auto-restart capability.

The VIPER22ASTR-E integrates a high-voltage startup current source, PWM controller, and power MOSFET in a monolithic design. At startup, the internal current source charges the VDD capacitor through the drain pin until the UVLO threshold is reached. The PWM controller then begins switching the MOSFET at 60kHz, regulated by current-mode control. The feedback pin (FB) receives current from an optocoupler or auxiliary winding, controlling the duty cycle. When the output is lightly loaded, the device automatically enters burst mode by skipping switching cycles, reducing power consumption. Protection circuits monitor VDD for overvoltage, junction temperature for overtemperature, and drain current for overcurrent conditions.

• Small power AC-DC adapters and battery chargers (5-12W)
• TV and monitor standby power supplies
• LED lighting driver power supplies
• Motor control board auxiliary power
• Smart meter and IoT device power modules