Load-powered relay enables battery‑less designs
The Littelfuse CPC1601M is an ultra-compact solid-state relay which operates without the need for a dedicated power supply, simplifying the design of systems requiring a reliable isolated power switch.
The CPC1601M, a 1FormA solid-state latching relay, supports load-powered operation, enabling it to harvest operating power from the open-circuit load itself and draw zero current from the system supply. This means the CPC1601M can switch ac or dc loads without needing a dedicated power supply.
The relay’s latching design requires only momentary pulses on its Set, Reset or Toggle inputs to change state, consuming no coil-hold current. A zero-current switching feature ensures the relay opens at or near zero load current when in load-powered mode, minimizing inductive kickback and electrical noise.
Featuring low on-resistance, the CPC1601M handles loads with minimal conduction loss. As a solid-state device, it has no moving parts and operates silently and reliably, unlike electromechanical relays.
These capabilities make the CPC1601M ideal for battery-powered or retrofit control systems. In smart thermostats and two-wire heating, ventilation and air conditioning installations, it removes the need for a common power wire, simplifying upgrades in older buildings. Its silent operation and long electrical life lend themselves to use in security panels and fire alarm systems, in which maintenance-free and noise-free switching is crucial.