Compact UL 1577 Certified Photorelay For Factory Automation


Many applications such as semiconductor test systems require numerous relays creating a strong need for smaller photorelays, thereby supporting the development of smaller and thinner products. Furthermore, unlike mechanical relays, photorelays have no physical contacts that incur wear and tear, contributing to significantly increased reliability. Photorelays also offer lower power consumption as well as excellent switching characteristics (high speed, low noise). They are therefore being considered by engineers to replace mechanical relays.

New Compact Photorelay For Industrial Applications 

Toshiba has released a new compact photorelay, the TLP3122A, for factory automation and other industrial applications including building automation, security and semiconductor testing. Offered in a small 4-pin SO6 package, the normally-open TLP3122A serves as a replacement for 1-Form-A mechanical relays to improve system reliability and save the space required for relays and relay drivers.

In addition, the TLP3122A is rated for an operating temperature between -40°C and 110°C which is ideal for industrial applications and makes it easier to allow for a temperature margin in system-level thermal design.


The new photorelay integrates MOSFET devices fabricated using the latest U-MOS IX process to reduce on-state resistance, Toshiba said.

The new TLP3122A is upward compatible with the company’s TLP3122 device in the conventional 2.54SOP4 package. Toshiba notes the new photorelay also helps increase the system drive current, making it possible to serve as a replacement for a wider range of mechanical relays.

Applications of the new Photorelay:

  • Industrial equipment (PLC, I/O interface)
  • Building automation systems
  • Semiconductor testers
  • Security equipment
  • Replacement of mechanical relays(AC 24V to 32V system, DC24 to 48V system)

Key features of the new Photorelay:

  • 4-pin SO6 small package: 2.54mm (pitch), 2.1mm (height); 4-pin package
  • Normally opened (1-Form-A)
  • OFF-state output terminal voltage 60V (max.)
  • Constant current 1.4A (max.)
  • ON-state current (pulse) 4.2A (max.)
  • Low-On-Resistance: 0.25Ω (max.)
  • Operating temperature: 110°C (max.)
  • Safety standards: UL-approved (UL1577) ; isolation voltage 3750Vrms (min.)
SMD Shunts Now In 0.2 mΩ

Volume shipment of the new photorelay has begun.



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