Offline switcher with 730 V avalanche-rugged MOSFET
The VIPER12AS-E is an offline switching regulator from STMicroelectronics' VIPER™ series, integrating a 730 V breakdown power MOSFET and a PWM controller in a single 8-SOIC package. It delivers up to 8 W in non-isolated flyback or buck topologies, making it a compact solution for auxiliary supplies in appliances, industrial controls, and smart meters. The 730 V avalanche-rated MOSFET provides enough headroom for universal mains input (85–265 VAC) plus line surges, reducing the need for external clamping circuits. This is a key reliability factor in high-line environments or regions with unstable grid voltage.
60 kHz fixed-frequency PWM with built-in protection
Switching at 60 kHz, the VIPER12AS-E uses a fixed-frequency PWM architecture that simplifies transformer design and EMI filter sizing. The internal oscillator is trimmed to ±5 % typical, so the switching noise spectrum is predictable across production lots. On-chip fault protection covers current limiting, over-temperature shutdown, and over-voltage lockout. These features eliminate the need for a separate supervisor IC and allow the part to survive output short circuits or fan failures without damage. The start-up voltage is 14.5 V, with an operating supply range of 9 V to 38 V on the Vcc pin. This wide Vcc window accommodates self-supplied bias windings or auxiliary rails from a downstream regulator.
Industrial temperature grade and SOIC-8 footprint
Rated for junction temperatures from -40°C to 150°C, the VIPER12AS-E suits environments where ambient heat exceeds 85°C — such as motor-drive auxiliary supplies, outdoor LED lighting, and industrial PSUs. The 150°C absolute maximum junction temperature allows operation under full load even when the thermal resistance of the 8-SOIC package is high. The 8-SOIC (0.154-inch body width) footprint is a standard surface-mount package that reflows on a standard lead-free profile. The copper pad area under the IC on the PCB should be maximised to dissipate heat from the internal MOSFET; a 1 oz copper pour of at least 300 mm² is typical for 8 W designs.
Active production with ROHS3 compliance
STMicroelectronics lists the VIPER12AS-E as Active. This supports long-term production commitments without last-time-buy risk. The base product number is VIPER12, indicating this is the standard 8 W variant in the VIPER family. The 'S' suffix denotes the SOIC-8 package; the '-E' suffix is the ROHS3-compliant version.