TOSHIBA Photocoupler IRED & Photo-Transistor TLP572 Programmable Controllers AC/DC-Input Module Solid State Relay TLP572 Unit: mm The TOSHIBA TLP572 consists of a Darlington connected phototransistor optically coupled to an infrared emitting diode in a six lead plastic DIP package. TLP572 has no-base internal connection for high-EMI environments. Collector-emitter voltage: 55 V (min) Current transfer ratio: 1000% (min) Isolation voltage: 2500 Vrms (min) .