LTV-844S is a 4-channel, transistor-output photocoupler (opto-coupler). Its core function is to provide electrical isolation between two independent circuits while transmitting digital signals. By utilizing internal light-emitting diodes (LEDs) and phototransistors, it employs light as the medium to transfer electrical signals from the input side (control circuit) to the output side (load circuit), while maintaining complete electrical isolation between them.