Littelfuse CPC1601M Load-Powered Latching Relay Simplifies Smart HVAC and Building Control Designs

Ultra-compact relay enables battery-less or low-power operation for thermostats, building automation, HVAC, and security systems.

ROSEMONT, Ill., November 18, 2025 — Littelfuse, Inc. (NASDAQ: LFUS), an industrial technology manufacturing company empowering a sustainable, connected, and safer world, today announced the launch of the CPC1601M, an innovative 60 V, 2 A normally open (1-Form-A) solid-state latching relay designed to address critical integration and power efficiency challenges in thermostats, HVAC systems, and building automation. (View the video.)

The CPC1601M is the first PCB-mounted solid-state relay of its kind that combines load-powered operation with a latching architecture in a 3 × 3 mm DFN package. Its ability to harvest operating power directly from the load or draw less than 1 μA from the system supply enables zero-power operation, dramatically extending battery life or eliminating the need for batteries.

“With the launch of the CPC1601M, we’re giving our customers a powerful new tool to design smarter, more efficient control systems, especially in space-constrained and energy-sensitive applications like building automation,” said Dr. Hugo Guzman, Product Marketing Manager at Littelfuse. “This innovative SSR (relay) reduces system power consumption through its unique load-powered operation and simplifies integration into both modern and legacy installations. It’s a natural extension of our solid-state relay portfolio, reinforcing our commitment to solving real-world design challenges with compact, reliable, and forward-thinking solutions.”

Solving Real-World Challenges

For engineers designing smart thermostats and two-wire control systems, the CPC1601M removes the need for a common (C) wire, simplifying installations, especially in older buildings. Its solid-state operation also eliminates clicking sounds and moving parts, offering a silent and long-lasting alternative to mechanical relays.

End-users benefit from slimmer, quieter, and maintenance-free devices, while installers save time and cost by avoiding additional wiring or external power kits.

Features and Benefits

• Latching relay architecture requires only a single pulse to change states, minimizing energy draw.
• Harvest mode enables operation using only the open-circuit load—no system power required.
• Power output pin provides up to 10 mW to external circuits, supporting additional low-power functions.
• Compact 3 × 3 mm DFN package reduces PCB footprint and enables ultra-thin device profiles.
• Zero-cross switching reduces electrical noise and improves reliability in AC loads.
• TTL/CMOS-compatible inputs ensure easy integration with microcontrollers or logic circuits.

Markets and Applications

• Smart thermostats
• Fire alarm panels
• Security and access control systems
• Building and HVAC automation
• Industrial control systems
• Utility metering and instrumentation

The CPC1601M marks a significant expansion of the Littelfuse solid-state relay portfolio, reinforcing its position as a leader in innovative switching solutions for next-generation control systems.

Availability

These solid-state relays are available in quantities of 2,000 per reel. Sample requests are accepted through authorized Littelfuse distributors worldwide. For a listing of Littelfuse distributors, please visit Littelfuse.com.