TOKYO—Toshiba electronic Devices & Storage Corporation ("Toshiba") has launched “TLP3910,” a photovoltaic-output photocoupler (“photovoltaic coupler”) housed in a thin SO6L package, suitable for driving the gates of high-voltage power MOSFETs used as isolated solid state Relay (SSR) function. Volume production shipments start today.
An SSR is a kind of Semiconductor relays that has a photo triac, a photo transistor or photo thyristor as its output device. It is suitable for applications for performing ON/OFF control of large currents.
A photovoltaic coupler is a photorelay with its optical devices but without the mosfet used to perform switching functions. In configuring an isolated SSR, high-voltage, large-current switching, which photorelays handle with difficulty, can be implemented easily by combining a photovoltaic coupler and a MOSFET.
Driving a high-voltage power MOSFET with a gate voltage of 10V or higher, requires connecting two of Toshiba’s current product, the TLP3906, in series, as it has a low open voltage. In contrast, the new TLP3910 has a minimum open voltage of 14V, double that of TLP3906, and only one is required to drive the gate of a high-voltage power MOSFET. This contributes to part-count reduction.
Improvement to the built-in discharge circuit has realized a typical turn-off time of 0.1ms, about 1/3 that of TLP3906 and about 1/30 that of TLP191B, and this delivers higher speed operation.
TLP3910 is Toshiba’s first photovoltaic coupler to feature a minimum isolation voltage of 5000Vrms while maintaining the basic performance of the current products, TLP191B and TLP3906. This allows use in industrial equipment driven by AC400V systems. The scope of application has also been extended by its high-temperature operation of 125°C.
 In isolated SSRs, the primary and secondary sides are electrically isolated. Switching a circuit connected to the AC line and between devices with different ground potential can be controlled through the isolation barrier.
 Among photovoltaic couplers, Toshiba survey as of May 27, 2021.
Isolated SSRs: gate drive of high-voltage power MOSFETs for switches.
- Industrial equipment: relay contact output for I/O of programmable logic controllers and the like; solenoid driver control parts of braking systems; main power supply circuits/inrush current protection circuits; battery voltage monitoring parts for battery management systems (BMS); ground fault detection parts.
- Measuring equipment: power supply line switching; measuring line switching
- High open voltage: VOC=14V (min)
- Short-circuit current: ISC=12μA (min) @IF=10mA, (C20 rank product) ISC=20μA (min) @IF=10mA
- High isolation voltage: BVS=5000Vrms (min)
- High operation temperature rating: Topr (max)=125°C
- Creepage(Space Distance): 8mm (min)