Littelfuse Launches CPC1601M Load-Powered Solid-State Relay for Smart Thermostats and HVAC Automation

Littelfuse has introduced the CPC1601M, a 60 V, 2 A normally open (1-Form-A) solid-state latching relay in a 3 × 3 mm DFN package for thermostats, HVAC systems, and building automation.

The relay supports load-powered operation, harvesting power from the load or drawing less than 1 μA from the system supply for zero-power functionality.

Dr. Hugo Guzman, Product Marketing Manager at Littelfuse, stated that the CPC1601M addresses integration and power efficiency in space-constrained applications like building automation. He noted it reduces system power consumption and simplifies integration into modern and legacy installations.

For smart thermostats and two-wire control systems, the relay eliminates the need for a common (C) wire. Its solid-state design avoids clicking sounds and moving parts compared to mechanical relays.

Features include latching architecture requiring a single pulse to change states; harvest mode using open-circuit load without system power; a power output pin providing up to 10 mW to external circuits; compact 3 × 3 mm DFN package; zero-cross switching for AC loads; and TTL/CMOS-compatible inputs for microcontroller integration.

Applications cover smart thermostats, fire alarm panels, security and access control systems, building and HVAC automation, industrial control systems, utility metering, and instru...