Littelfuse Simplifies Smart HVAC and Building Control with Load-Powered Latching Relay

Power efficiency has become one of the biggest challenges in smart building and HVAC design. Devices are expected to run for years with minimal power, yet still deliver accurate control and wireless connectivity. Littelfuse’s new CPC1601M solid-state relay takes a fresh approach by powering itself directly from the circuit it switches.

A Relay That Powers Itself

The CPC1601M is a 60 V, 2 A normally-open solid-state relay built into a 3 × 3 mm DFN package. Instead of relying on a separate supply, it can draw energy from the load itself or use less than one microamp from the system power rail. That ability means thermostats and controllers can run without an extra power wire or even a battery, which is particularly useful when upgrading older installations.

Its latching design also helps save energy. The relay only needs a short control pulse to change state, and once it switches, it stays that way until the next pulse. There’s no continuous holding current and no mechanical contacts to wear out or make noise.

Simpler Integration for Building Systems

For engineers working on two-wire HVAC or control systems, the CPC1601M can remove the need for a common (C) wire entirely. The solid-state design operates silently, while zero-cross switching helps cut electrical noise when switching AC loads. It also includes a small output pin that can supply about 10 mW to other low-power circuits, and its TTL/CMOS-compatible inputs make it easy to connect straight to a microcontroller.

Compact, Efficient, and Quiet

At just 3 mm square, the relay is small enough for slim thermostat housings and other compact control devices. With no moving parts, it offers quiet operation and a long service life. Combined with its ability to harvest its own power, it gives engineers a way to build maintenance-free systems that are both efficient and reliable.

For smart HVAC, security, and building-automation designs where wiring and energy budgets are tight, the CPC1601M shows how solid-state switching can make everyday control hardware simpler and more sustainable.

Learn more and read the original article on www.littelfuse.com