800 V breakdown — the headroom for universal AC
The VIPER114HSTR integrates an 800 V avalanche-rated MOSFET and a 120 kHz PWM controller in a single 10-SSOP package, targeting off-line power supplies up to 12 W in buck, buck-boost, or flyback topology. The 800 V breakdown gives enough margin for universal AC input (85–265 VAC) with reflected voltage and leakage spike headroom, so you are not riding the avalanche limit on a 230 V line. Internal soft-start and a full set of protections — current limiting, over-load, over-voltage, and short-circuit — are on-die, meaning fewer external components on the BOM.
12 W in a 10-SSOP — thermal reality
At 12 W output in a flyback, expect the junction to rise; the 10-SSOP package relies on the PCB copper area for heat sinking. The 125°C Tj rating gives room for a 70–85°C ambient in a ventilated enclosure, but a sealed plastic housing will need a layout with a solid ground-plane island under the IC. The 4.5 V to 30 V Vcc range means the auxiliary winding can drop well below the start-up threshold (16 V) once the converter is running, and the chip stays alive on a lower rail.
It is a current-production part in the VIPER family.