STMicroelectronics is aiming at mains power supplies up to 8W, wasting as little as 40mW with no load with VIPer222, a control chip that includes a 730V power switch.

Despite coming in a 5 x 6 x 1.75mm SSO10 package with only 10 pins, it can used in a several topologies including:

• Non-isolated fly-back
• isolated fly-back
• primary-side regulated
• secondary-side opto-coupler feedback
• buck
• buck-boost (negative output)

The power switch is an avalanche-rugged current-sensing mosfet, and operation is over a Vcc range of 4.5V-30V, “which allows the device to be powered whatever the desired output voltage”, claimed the company.

There are two versions, operating at either 30 or 60kHz, both with a jittered PWM to reduce the size of filter components.

Protections include short-circuit and thermal, and soft-start is implemented over 8ms at switch-on and after a fault. Burst-mode operation enhances efficiency at light load.

Applications are foreseen in home appliances, building-automation devices, smart lighting, and smart meters.