Automotive Product of the Year
Product Name: TLX9160T
Introduced by Toshiba in January 2022, the TLX9160T is a fully AEC-Q101 qualified photorelay device which offers attributes that will be vital for next generation electric vehicle (EV) powertrains. It basically provides a way of bridging the gap that currently exists between conventional electro-mechanical methods of delivering isolation and the convenience, compactness and reliability that a solid-state approach to isolation offers. Key to this is the 1.5kV output withstand voltage (VOFF) that it is capable of supporting.
Previously, high-voltage isolation required use of electro-mechanical relays. However, though they could deal with elevated voltages, these components have certain operational lifespan limitations, due to wearing of their contact surfaces. Another concern here has been the potential for these contacts to stick, and the dangers this could cause.
The substitution of electro-mechanical relays with optoelectronic equivalents clearly has significant benefits for automotive manufacturers. Photorelays are much more compact, meaning that they can save valuable space within automobile designs. Since they rely on infrared (IR) light and do not have any physical contacts, their functioning is not affected by wear-and-tear. As a result, they will continue to work for much longer periods.
The main issue holding back the adoption of photorelays for EV powertrain isolation until now, was the inability of such devices to cope with the high voltages that will be present within the new generation of models that are now under development. In order to make their EVs more efficient, automotive companies are looking to implement powertrains where the voltage levels have been raised. This means that 400V-rated systems will be phased out in favour of ones supporting 800V.
Such voltages are generally beyond what photorelays are able to handle, which has been seriously problematic – as automobile manufacturers want to avoid the specifying of electro-mechanical relays for this purpose and use more streamlined, reliable and power efficient solutions instead. This is why the Toshiba TLX9160T is a real differentiator – presenting EV manufacturers with a normally-open 1-Form-A photorelay device that is suitable for handling EV supply voltage (VDD) figures of 1kV.
The TLX9160T has a much higher voltage MOSFET between its output terminals of the light-receiving photodiode array than actually available photorelays. Thanks to the enhanced voltage capabilities of its MOSFET, this photorelay is ready for the transition of EV powertrains to higher voltage values. When deployed into 1kV systems, creepage and clearance distances of 5mm are maintained by the device on its output side.
Another important attribute of the TLX9160T is its rapid responsiveness, with a maximum turn-on/off time below 1ms and a trigger current of no more than 3mA being needed. It has an off-state current (IOFF) of just 100nA at room temperature, thereby minimising power consumption when not active. The IR emitter element has a maximum forward current (IF) of 30mA (though 10mA is typically recommended), while its photodiode element has an on-state current (ION) of 50mA.
The automotive-grade TLX9160T is supplied in modified SO16L-T package, with 10.3mm x 10.0mm × 2.45mm dimensions. The resin material used in the construction of this device has a >600 comparative tracking index (CTI), giving it exceptional resilience to electrical breakdown situations. An operational temperature range of -40°C to +125°C is supported by the device, allowing it to contend with harsh working conditions. Key applications for this photorelay include EV battery management system (BMS) implementations, as well as ground fault detection and determining faults in mechanical relays.