Toshiba launches compact automotive photorelay with high breakdown voltage support for EV battery systems
21st August 2025
Toshiba Electronics Europe GmbH (“Toshiba”) introduces its new automotive photorelay, the TLX9161T. Housed in a small SO12L-T package, the device achieves an output withstand voltage (VOFF) of 1500V (min.) with a reaction time (TON/TOFF) of 1ms (max.). This capability is crucial for supporting the demanding high-voltage requirements of modern automotive battery and fuel-cell control and battery management systems (BMS), which monitor voltage and detect mechanical relay sticking and ground faults. These photorelays are also ideal for replacing traditional mechanical relays.
The TLX9161T consists of an infrared (IR) light-emitting diode (LED) optically coupled to a photo-MOSFET, ensuring that the primary (control) side and the secondary (switch) side are electrically isolated. The high isolation voltage of 5000Vrms enables safe switch control across varying potentials. The trigger current (IFT) is 3mA (max.), which minimises system energy consumption. Furthermore, this device’s off-state current (IOFF) is just 100nA (max.) at ambient temperature, drawing minimal power while inactive. The IR LED forward current (IF) and the detector element’s on-state current (ION) are both rated at 30mA ambient.
By reducing the size of the built-in MOSFET chip, Toshiba has enabled the new TLX9161T photorelay to be housed in a SO12L-T package, which is approximately 25% smaller than the SO16L-T package used for its predecessor, the TLX9160T. This reduction helps minimise the overall size of the battery unit and allows for cost savings. Despite the smaller package, the TLX9161T maintains the same pin pitch and pin layout as the SO16L-T, allowing for common use of circuit board pattern designs. The typical dimensions of the SO12L-T package are 7.76mm × 10.0mm × 2.45 mm.
Safety and compliance are paramount in automotive applications. The TLX9161T utilises a resin with a Comparative Tracking Index (CTI) exceeding 600, classifying it under Material Group I according to the international standard IEC60664-1. This standard specifies principles, requirements, and test methods for insulation coordination for systems up to 1000VAC or 1500VDC. The normally-open (1-Form-A) device exhibits creepage and clearance distances of 8mm (min.), confirming effective isolation even in operating temperatures ranging from -40 to +125°C, making it fully compliant with AEC-Q101 Grade 1.
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