STMicroelectronics’ SRK1004 synchronous-rectifier controller eases the design and enhances the efficiency of converters built with silicon or GaN transistors, including industrial power supplies, portable device chargers, and AC/DC adapters.

Capable of withstanding up to 190 V at its sense input, the SRK1004 can be connected in a high-side or low-side configuration. Four variants let users avoid complex calculations by optimizing their design through device selection alone, selecting gate-drive voltage between 5.5 V and 9 V, with logic-level MOSFETs, standard MOSFETs, or GaN transistors. Suitable for noncomplementary active clamp, resonant, and quasi-resonant (QR) flyback topologies, the SRK1004 introduces a next-generation turn-off algorithm that simplifies operation and saves energy.

The features of this controller enable converters to provide a high output power rating within compact dimensions. The operating frequency can be up to 500 kHz, allowing the use of small magnetic components as well as maximizing the benefits of wide-bandgap technology when using GaN transistors. The controller is fabricated in ST’s silicon-on-insulator (SOI) process, which ensures robust performance while permitting a tiny 2 mm x 2 mm DFN-6L package.

By operating with a supply voltage from 4 V to 36 V, the SRK1004 can be powered from a variety of standard industrial bus voltages. The wide input-voltage range also provides flexibility to adjust the step-down ratio for optimum efficiency. Also, with fast-acting short-circuit detection built-in, the controller helps build rugged and reliable equipment.

Of the four variants introduced, the SRK1004A and SRK1004B are configured for 5.5 V gate-drive voltage and can be used with logic-level MOSFETs or GaN transistors. The SRK1004C and SRK1004D for 9V gate-drive voltage are suited to MOSFETs designed for standard gate-drive signals.