Requirements to support both sink and source logic inputs in modern PLC and instrumentation systems means that bridge circuitry is commonly employed upstream from the photocouplers used in high-speed digital interfaces. Now, however, by combining two LEDs in a reverse parallel configuration, the TLP2395 and TLP2398 eliminate the need for these bridge circuits. As a modern PLC can have multiple photocouplers - and, therefore, multiple bridge circuits - the devices will significantly reduce circuit size, power consumption and cost.
Both the TLP2395 (logic buffer output) and the TLP2398 (inverter output) photocouplers will accommodate a 3 to 20V power supply voltage range, which helps to reduce the need for DC-DC conversion circuitry. Each device also offers guaranteed operation at temperatures ranging from -40°C to 125°C. Toshiba’s new devices support a data transfer speed of 5 Mbps and combine a propagation delay of less than 250 nsec with a pulse width distortion below 80 nsec. As a result they are suitable for RS232C, RS422, RS485 and other commonly used industrial communication interfaces. Input current drive of 2.3 mA and a supply current of 3 mA contribute to application efficiency.
The couplers are supplied in SO6 surface mount packaging that integrates two GaAlAs LEDs coupled with a high-gain, high-speed photodetector. Dimensions are 7.0 x 3.7 x 2.3 mm, guaranteed minimum creepage and clearance distance is 5 mm and guaranteed minimum input-output withstand voltage is 3.5 kVrms. An internal Faraday shield ensures common-mode transient immunity of ±20 kV/μsec.