Toshiba Introduces Compact Automotive Photorelay Delivering 1500V Withstand Voltage for Next-Generation EV Battery Systems
Toshiba Electronic Devices & Storage Corporation (Toshiba) has announced the launch of its latest innovation in the field of automotive semiconductor technology—a new automotive photorelay, model TLX9161T. Designed in a compact SO12L-T package, this device delivers an output withstand voltage of 1500V (minimum), meeting the demanding requirements of high-voltage automotive battery systems. Volume shipments have officially begun, marking a significant milestone for both Toshiba and the broader electric vehicle (EV) ecosystem.
This development comes at a pivotal moment for the global automotive industry. As electric vehicles become increasingly mainstream, automakers and component suppliers are racing to improve efficiency, safety, and performance in battery management systems (BMS). Toshiba’s latest product directly addresses several of these challenges, offering high performance in a smaller form factor while helping to reduce overall system size and cost.
The Growing Demand for Advanced Battery Management
One of the major hurdles in accelerating EV adoption lies in battery technology. Consumers demand longer driving ranges and faster charging, but these improvements require not only better battery chemistry but also more intelligent and efficient management systems.
A Battery Management System (BMS) plays a critical role by monitoring charge status, balancing cells, and ensuring that batteries operate within safe voltage and temperature limits. Importantly, BMS technology must also monitor the isolation between the high-voltage battery and the vehicle body to prevent leakage currents or potential electric shocks.
This is where electrically isolated switching components—such as photorelays—become essential. By providing safe electrical isolation between control and power circuits, photorelays enable reliable operation under high-voltage conditions. Toshiba’s TLX9161T is specifically engineered to serve these demanding applications, enhancing both safety and efficiency in EV battery systems.
Evolution from TLX9160T to TLX9161T
The newly introduced TLX9161T is a miniaturized version of Toshiba’s existing TLX9160T photorelay, which already enjoys wide adoption in high-voltage applications. The advancement comes from shrinking the built-in MOSFET chip, allowing Toshiba engineers to integrate it into the smaller SO12L-T package.
- The SO12L-T package measures just 7.76 × 10.0 × 2.45 mm, offering about a 25% reduction in mounting area compared to the larger SO16L-T package used in the TLX9160T.
- Despite its smaller size, the new model retains the same pin pitch and layout as its predecessor. This means existing circuit board designs can be reused, providing manufacturers with an easy migration path while saving redesign costs.
This combination of higher voltage withstand capability and miniaturization is particularly valuable for automakers, who are under constant pressure to optimize packaging space, reduce component costs, and improve energy efficiency.
Materials and Safety Compliance
Toshiba has also ensured that the TLX9161T meets international safety standards. The device uses a high-performance resin with a Comparative Tracking Index (CTI) greater than 600, which falls under Material Group I in the IEC 60664-1 standard.
- CTI measures the ability of insulating materials to withstand electrical stress without forming conductive paths across the surface. A higher CTI value indicates stronger insulation reliability.
- In this case, exceeding 600 means the material offers excellent resistance to electrical tracking, critical for long-term reliability in high-voltage automotive environments.
Additionally, the photorelay’s pin configuration provides a creepage distance of more than 5 mm on the detector side. Combined with the resin’s properties, this allows compliance with IEC 60664-1 insulation coordination standards, supporting operating voltages up to 1000V in automotive environments.
This level of compliance is crucial, as EV battery systems can operate at voltages as high as 800V to 1000V. The TLX9161T ensures safety in these conditions, making it an ideal choice for next-generation vehicles.
Technical Features of the TLX9161T
The TLX9161T comes with several standout technical features that make it highly competitive in the EV component market:
- Compact Package: SO12L-T, measuring 7.76 × 10.0 × 2.45 mm (typical)
- High Output Withstand Voltage: VOFF = 1500V (minimum)
- Normally Open (1-Form-A) Device: Ensures reliable switching in BMS circuits
- Avalanche Current Rating: IAV = 0.6 mA, ensuring robustness against sudden current surges
- High Isolation Voltage: 5000 Vrms (minimum) between input and output
- AEC-Q101 Qualified: Meeting automotive reliability standards required by global automakers
- IEC 60664-1 Compliance: For insulation coordination up to AC 1000V or DC 1500V systems
These features collectively ensure that the TLX9161T is not only compact but also highly reliable under extreme operating conditions, a critical factor for automotive applications.
Applications in Automotive Systems
The TLX9161T is designed for multiple use cases within automotive electrical systems, particularly within Battery Management Systems. Some key applications include:
- Battery Voltage Monitoring: Ensures accurate tracking of cell voltages in large battery packs.
- Mechanical Relay Sticking Detection: Helps detect failures in conventional relays, improving system safety.
- Ground Fault Detection: Identifies potential leakage currents between the high-voltage battery and the vehicle chassis.
- Replacement of Mechanical Relays: Provides a solid-state alternative that is more compact, durable, and reliable.
As automakers transition from mechanical relays to solid-state relays, photorelays like the TLX9161T offer a clear advantage by eliminating mechanical wear and tear, improving response time, and enhancing long-term system reliability.
Contribution to EV Growth and Sustainability
Beyond technical performance, Toshiba’s launch of the TLX9161T also speaks to the company’s broader mission of supporting the transition toward a carbon-neutral society. By providing advanced semiconductor solutions for electric vehicles, Toshiba is enabling faster charging, safer operation, and ultimately a smoother path toward widespread EV adoption.
The company has emphasized its commitment to expanding its lineup of automotive photorelays, ensuring that future models will continue to meet the evolving needs of EV manufacturers worldwide. With governments setting ambitious timelines to phase out internal combustion engine vehicles, these technologies are poised to play a crucial role in achieving sustainable transportation goals.
