Offline flyback switcher runs aux power in industrial, appliance design

January 18, 2017 // By Graham Prophet
Power Integrations’ LinkSwitch-XT2 family of offline, low-power converter ICs are rugged devices with excellent no-load performance, suitable for low-power applications including appliances, IoT, metering and industrial bias power.

The converters offer offering high accuracy and high efficiency for isolated and non-isolated flyback applications in which accurate regulation of output voltage and current are important. They can deliver up to 6.1W in wide-input range designs, and up to 9.2W for 230 VAC open-frame applications.


Designed for flyback topologies, the ICs enable designs that exhibit current and voltage regulation of better than ±3% and typical efficiency above 80%. LinkSwitch-XT2 ICs consume less than 10 mW in no-load conditions. High (132 kHz) operating frequency enables the use of small power transformers, while the programmable current limit (I LIM) function enables further transformer optimization.


LinkSwitch-XT2 converters combine a 725 V power MOSFET with control circuitry on a single silicon die. Integrated safety and reliability features include input overvoltage protection, hysteretic thermal shutdown for over-temperature protection, and auto-restart for output short-circuit, overvoltage and open-loop protection. PI presents them as being suited for small appliances such as microwave ovens, IoT applications, utility meters, industrial and smart-home installations.


In three packages: P-package (DIP-8C), D-package (SO-8C), and G-package (SMD-8C), they are priced at $0.40 (10,000)-piece quantities. A reference design DER-578, which details a 5V 500 mA power supply, is available from;


Power Integrations;