Photovoltaic-output photocoupler with increased open voltage for isolated SSRs

12-07-2021 | Toshiba | Power

Toshiba Electronics Europe GmbH has released a new photovoltaic-output photocoupler housed in a thin SO6L package measuring only 3.84mm x 10mm x 2.1mm, ideal for driving the gates of high-voltage power MOSFETs employed to develop a galvanically-isolated solid-state relay function.

A photovoltaic coupler, such as the new TLP3910, is a photorelay that incorporates the optical elements but not the MOSFET performing the high-current switching functions. To simply configure an isolated SSR to handle high-voltage, large-current switching, designers commonly combine a photovoltaic coupler with a MOSFET.

Driving a high-voltage power MOSFET with a gate voltage of 10V or higher currently needs connecting two of the company's TLP3906 in series due to the low open voltage that is around 7V. However, the new device has a minimum open VOC of 14V, double that of the TLP3906, and, as a result, only a single device is needed to drive the gate of a high-voltage power MOSFET. This decreases the part count, which improves reliability and saves PCB space and BOM cost.

The device is the company's first photovoltaic coupler to provide a minimum isolation voltage (BVS) of 5000Vrms while supporting the excellent performance of the current products (TLP191B and TLP3906). This, along with the creepage distance of 8mm and relevant UL/cUL approvals, enables use in industrial equipment driven by 400VAC systems and other applications where electrical safety is paramount.

The high-temperature operation range of -40C to +125C assures that the device is ideal for a broad variety of rugged applications.

By Natasha Shek