Littelfuse Launches Solid-State Relay IC with Integrated Chime Bypass for Video Doorbells

Littelfuse has released the CPC2501M, a compact, application-specific solid-state relay IC designed to simplify the integration of modern video doorbell systems with traditional household chimes. Developed as a self-actuating, normally closed relay, the CPC2501M provides a plug-and-play solution to bypass mechanical chimes, solving a common problem in smart home upgrades. With the growing popularity of video doorbells, many users face issues when retrofitting these devices into homes wired for legacy 8–24 VAC systems and mechanical chimes. The CPC2501M is purpose-built to manage this challenge. It enables continuous power delivery to the doorbell camera while maintaining full chime functionality, eliminating the need for external relays, added control logic, or specialised installation steps. “The CPC2501M chime bypass relay enables video doorbell manufacturers to make their product work with existing house installations,” said Hugo Guzman, Product Marketing Manager at Littelfuse. “End users can replace the doorbell button with a new video unit using the existing door chime box, no added circuitry needed.”

Compact, Self-Protecting Design

The CPC2501M integrates solid-state switching, self-actuating logic, and fault protection into a single 6 x 6 mm QFN-16 package, conserving PCB space and reducing component count. It requires no external microcontroller or software to operate. Key features include:

• 60 VP bidirectional switching and 1.84 ARMS continuous load current
• 5 A peak current handling for inrush or surge conditions
• Built-in fault protection timer (~17 seconds) for long button presses or chime failure
• Thermally optimised package for space-constrained designs

The IC is installable behind standard low-voltage doorbell transformers and is supplied in tape and reel for high-volume production, with sample quantities also available through Littelfuse’s global distribution network.

Improving System Performance Without Complex Retrofitting

During normal operation, the CPC2501M enables a power bypass when the chime is idle and disconnects that path instantly when the doorbell is pressed, ensuring uninterrupted power to the video system and restoring chime operation on demand. This approach ensures stable camera uptime without sacrificing chime functionality, making it ideal for both professional installers and DIY solutions.

Beyond Doorbells: Broader Application Potential

While engineered with video doorbell chime bypass in mind, the CPC2501M is also suitable for:

• Building automation systems
• Voltage-controlled IoT devices
• Compact switching in security panels
• General-purpose solid-state relay applications

By integrating logic and protection functions into a single IC, Littelfuse has created a reliable switching solution that simplifies design and installation across both consumer and industrial applications. To read the original press release, click here.