Reference design demos no-neutral BLE wall switch

-November 12, 2017

Power Integrations’ DER-622 document illustrates a Bluetooth Low Energy wall switch that does not require a neutral return wire to power the unit. It describes a smart wall switch that is compatible with retrofit wiring and LED lights, yet consumes less than 500 µA in standby mode.

The design example is based on the company’s LinkSwitch-TN2 offline switcher ICs. Configured to support flyback or buck topologies, LinkSwitch-TN2 devices provide voltage regulation of better than ±3%. The ICs integrate numerous safety features, including overvoltage, overtemperature, and short-circuit protection, as well as a 72 V power MOSFET.

In the DER-622 design example, the Linkswitch-TN2 power supply IC is used in a nonisolated flyback topology and employs half-wave AC input rectification. The power supply provides two outputs: a 12 V rail to drive a relay and a 3.8 V rail to power a Bluetooth Low Energy controller.

Key applications for the reference design include wireless lighting control, occupancy and vacancy sensors, motion detectors, wall dimmers, and shading controls. The 40-page DER-622 design example report is free for downloading from Power Integrations.

Power Integrations,

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