Power Integrations introduces a wall switch solution that eliminates the need for a neutral connection for wireless control of smart home lighting

Power Integrations recently released a new reference design, the DER-622. This is a smart wall switch that is compatible with the most common wiring conditions in residential retrofits.

In general, smart wall switches with wireless connectivity, human body sensing and/or voice control require a neutral connection to power the unit, a requirement that is sometimes difficult to meet in the case of retrofitting existing lines. Mid-line products are suitable for older incandescent bulb lighting applications because the AC input current that allows the leakage to the load to pass through the smart switch when in standby mode is small enough to heat the filament of the incandescent bulb. However, for LED lamps and compact fluorescent lamps, the current of the smart switch's internal power supply standby is relatively large, which can lead to unacceptable flicker, commonly referred to as "ghosting". This occurs because the energy accumulated in the bulb is accumulated, and this energy can cause intermittent startup and short-time illumination of the lamp.

The DER-622 is a Bluetooth low energy (LE) wall switch with standby current consumption less than 500 μA. The design is based on Power Integrations' LinkSwitch-TN2 off-line switching power supply IC, which consumes less than 75 μA of quiescent current. With ultra-low current consumption and high light-load efficiency, these ICs are compatible with energy-efficient LED bulbs rated down to 3 W and are suitable for mid-line wall switch wiring.

LinkSwitch-TN2 devices are configured to support flyback or buck topologies, providing high precision output with voltage regulation accuracy better than ±3%. This family of ICs integrates a wide range of safety features including input and output overvoltage protection, overtemperature protection, output short-circuit protection, and rugged 725 V power MOSFETs to enhance system reliability. In the DER-622, the LinkSwitch-TN2 power IC is used in a non-isolated flyback topology and uses half-wave AC input rectification to reduce solution cost. This power supply provides two outputs, 12 V for driving the relay and 3.8 V for powering the Bluetooth LE controller.

Hubie Notohamiprodjo, director of marketing for LED lighting products at Power Integrations, said: "Lighting control products such as smart wall switches and body-sensing sensors play an important role in improving the energy efficiency of homes and buildings. Many homes are not compatible with existing products or need to be Rewiring, which increases cost and hinders product adoption. The LinkSwitch-TN2 is easy to use and has ultra-low current consumption, making it a single-hot smart switching solution that is compatible with low-power LED bulbs and requires no neutral wiring applications. ."

Key applications include wireless lighting control, human body sensors, motion detectors, wall dimmers and shading controls.