TLP621,TLP621−2,TLP621−4 Programmable Controller AC / DC−Input Module Solid State Relay The TOSHIBA TLP621, −2 and −4 consists of a photo−transistor optically coupled to a gallium arsenide infrared emitting diode. The TLP621−2 offers two isolated channels in an eight lead plastic DIP, which the TLP621−4 provides four isolated channels in a sixteen plastic DIP. Collector−emitter voltage: 55 V (min.) Current transfer rati 50% (min.) Rank GB: 100% (min.)