Toshiba launches dual polarity input photocouplers for PLCs

JAPAN: Toshiba Corp. announced the launch of high-speed photocouplers for programmable logic controllers (PLCs) which work with both plus and minus LED currents.

PLCs accept either sink logic input, used mainly in Japan, or source logic input, used mainly outside Japan. With globalization, bridge circuits are increasingly employed upstream from photocouplers used as PLC input interfaces, in order to provide support for both sink and source logic.

The new photocouplers, the buffer logic type "TLP2395" and the inverter logic type "TLP2398", support both sink and source logic by combining two LEDs in inverse parallel, thereby allowing omission of the bridge circuits. Since there are cases where a single board will contain multiple bridge circuits, employing the new photocouplers can support reductions in circuit size, power consumption and cost.

The operating power supply voltage range of the new products supports a wide range, between 3V and 20V, and high-temperature operation is possible with an operating ambient temperature up to 125°C. The photocouplers support a data transfer speed of 5Mbps.

With their wide operating power supply voltage range and temperature range, a propagation delay time under 250ns, pulse width distortion under 80ns and propagation delay skew of 130ns are guaranteed. These features make the new products suitable for communication interfaces (RS232C, RS422, RS485, etc.) in industrial applications. A low input current drive (2.3mA) and low supply current (3mA) are also realized, contributing to energy efficiency.