Toshiba Launches High-Voltage Photorelay for EV BMS

Toshiba Electronics Europe GmbH has launched the TLX9165T, an automotive photorelay housed in a 10-pin SO16L-T package, featuring a minimum output withstand voltage of 1800V. The device is designed to support battery management systems (BMS) for high-voltage 800V electric vehicle (EV) batteries and battery energy storage systems (ESS).

The wider adoption of EVs relies heavily on faster charging times and longer cruising ranges, both of which require more efficient battery system operation. Battery management systems (BMS) play a key role in this by monitoring charge status and insulation between the battery and vehicle body—critical for the safe use of high-voltage batteries. In high-voltage BMS setups, electrically isolated photorelays are essential. Likewise, energy storage systems (ESS), vital for efficient renewable energy use, employ similar BMS configurations.

Photorelays used in battery systems must typically withstand voltages around twice the system voltage, meaning over 1600V for an 800V system. Toshiba’s new TLX9165T photorelay meets this need with a minimum output withstand voltage of 1800V, thanks to a newly developed high-voltage MOSFET. This makes it well-suited for use in 800V systems.

The 10-pin SO16L-T package of the TLX9165T incorporates a resin with a Comparative Tracking Index (CTI) of 600 or higher, belonging to Material Group I of the international standard IEC 60664-1. Furthermore, its pin configuration ensures a creepage distance of 7.5mm or more on the light receiver side, which allows for an operating voltage of 1500V. The pin pitch and configuration are also identical to Toshiba’s existing SO16L-T packages (such as TLX9160T and TLX9152M), enabling the common use of PCB pattern designs.

The TLX9165T is a normally open (1-Form-A) device with an avalanche current rating of I_AV=0.6mA and a high isolation voltage of 5000V_rms (min.). It is AEC-Q101 qualified and fully compliant with the IEC 60664-1 international standard. Key applications for the TLX9165T include automotive equipment, particularly BMS for monitoring battery voltage, detecting mechanical relay sticking, and ground fault detection, as well as serving as a replacement for mechanical relays.