In many industrial, medical, and instrumentation systems, relays sit at an uncomfortable intersection of requirements. They need to provide meaningful isolation, handle higher load currents, survive elevated temperatures, and fit into increasingly dense PCB layouts. Meeting all of those constraints at once is not trivial, particularly when designs are expected to operate reliably for years with minimal maintenance.
Littelfuse’s new CPC1343G OptoMOS® solid-state relay is aimed at those design scenarios. The device is a normally open, 1-Form-A solid-state relay rated for 60 V and 900 mA continuous load current, with reinforced isolation and extended temperature capability in a compact 4-pin package.
Reinforced Isolation in a Small Footprint
Isolation requirements are often driven by safety standards rather than functional needs. Medical equipment, industrial controls, and metering systems frequently require reinforced isolation to protect users, operators, and downstream electronics. Achieving that level of isolation in a small relay package can limit device options or force designers toward larger electromechanical components.
The CPC1343G provides 5,000 VRMS input-to-output reinforced isolation while maintaining a DIP-4 or surface-mount footprint. This allows designers to meet safety and compliance requirements without allocating excessive board area to the isolation barrier.
Because the isolation is inherent to the OptoMOS structure, the device avoids issues associated with contact spacing, arc suppression, or mechanical degradation that can arise in traditional relays over time.
Higher Current Without Excessive Thermal Penalties
Solid-state relays are often avoided in higher-current paths due to concerns around on-resistance and heat dissipation. As load current increases, even small resistance values can lead to localized heating that impacts reliability or forces additional thermal management.
The CPC1343G addresses this by offering a maximum on-resistance of 0.8 Ω, which helps reduce conduction losses at higher currents. Combined with a continuous load current rating of 900 mA, this makes the device practical for signal switching, control paths, and moderate-load applications where many compact SSRs fall short.
The relay is also rated for operation from –40 °C to +105 °C ambient temperature. That extended temperature range allows placement closer to power electronics or other heat sources without aggressive derating, which is especially useful in compact industrial and test systems.
Fast, Logic-Compatible Switching
In applications such as data acquisition, multiplexing, and automatic test equipment, switching speed and repeatability matter. Mechanical relays introduce variability through contact bounce and slower actuation times, which can limit test throughput or timing accuracy.
The CPC1343G offers a typical turn-on time of 4 ms and a turn-off time of 1 ms, supporting faster and more predictable switching behavior. This makes it suitable for designs where relays are part of active signal routing rather than simple on/off control.
On the input side, the relay requires a maximum LED drive current of just 3 mA. That low drive requirement allows direct control from TTL or CMOS logic without additional driver circuitry, simplifying interface design and reducing component count.
Reliability in High-Cycle and Harsh Environments
Because the CPC1343G is a solid-state device, it eliminates many of the failure modes associated with electromechanical relays. There are no contacts to wear, no audible noise during operation, and no mechanical parts affected by vibration.
These characteristics make the device well suited for systems that experience frequent switching, continuous operation, or challenging environmental conditions. Industrial automation equipment, utility meters, and instrumentation platforms often operate unattended for long periods, where maintenance access is limited and failure is costly.
Packaging and Application Fit
Littelfuse offers the CPC1343G in both through-hole DIP-4 and surface-mount packages, allowing it to fit into a range of manufacturing flows. Tape-and-reel options support automated assembly for higher-volume designs.
Target applications include industrial control systems, medical equipment requiring patient isolation, instrumentation and measurement platforms, automatic test equipment, and smart metering systems. In these designs, the relay typically sits between low-voltage control logic and higher-voltage domains, making isolation performance and long-term stability more important than raw switching speed alone.
By combining reinforced isolation, relatively high load current, and extended temperature operation in a compact form factor, the CPC1343G gives designers another option where traditional relays or lower-power SSRs create compromises elsewhere in the system.
Learn More: CPC1343G | 1-Form-A Series Normally Open Relays | Littelfuse
