Flyback switcher for 22 W isolated supplies
The VIPER35LD is an offline flyback switching regulator with an integrated 800 V power MOSFET, rated for 22 W output power in a flyback topology. It operates from a Vcc supply range of 8.5 V to 23.5 V and starts up at 14 V, suiting universal AC input designs with a properly sized transformer. The 136 kHz fixed switching frequency balances transformer size against switching losses, while the integrated fault protections — current limiting, over-temperature, over-voltage, and short-circuit — reduce external component count for compact PSU layouts.
Package and thermal considerations for 16-SOIC
Housed in a 16-SOIC package (0.154", 3.90 mm width), the VIPER35LD is a surface-mount part that reflows on standard solder profiles. The supplier device package is 16-SO, and the narrow body width keeps the footprint compact — expect to use a 4-layer PCB for adequate copper area on the drain-connected paddle to dissipate heat at full 22 W load. Derating the output power above 100°C ambient is recommended based on the thermal resistance of the 16-SOIC package.
The base product number is VIPER35, indicating this LD variant is a standard surface-mount version within the VIPER35 family. The 16-SO package is widely sourced through distribution channels.