Photo Relays With Low LED Trigger Current Replace Mechanical Relays

Düsseldorf, Germany: A series of semiconductor photo relays developed by Toshiba Electronics Europe is claimed to offer lower power consumption and reduced board space requirements when compared to mechanical alternatives.

Supplied in a compact SOP4 surface-mount package, the TLP170 photo relays measure 4.4mm by 3.9mm by 2.1mm. Each device comprises a gallium-arsenide infrared emitting diode that’s optically coupled to a MOSFET. The relays help lower power consumption thanks to an improved output photodiode array, which has reduced maximum LED trigger current of 1mA (versus the 3mA of previous devices).

Relays in the TLP170 series offer off-state voltages of 60V, 200V, 350V and 600V, satisfying a wide range of requirements. Potential applications range from security and measurement equipment to home appliances, office equipment, telecommunications products, and factory automation.

All of the new photo relays feature a normally open (1-Form-A) configuration and a minimum isolation voltage of 1500Vrms. Depending on the device chosen, maximum on-state current and on-state resistance ranges from 90mA to 400mA and 60Ω to 2.0Ω, respectively. Maximum turn-on time for all of the relays is 8.0ms, with maximum turn-off time specified as 3.0ms.

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