TLP387 Photocouplers Toshiba TLP387 Photocouplers incorporate an InGaAs infrared emitting diode optically coupled to a Darlington transistor. These TLP387 Photocouplers are housed in a 4-pin SO6L package with high noise immunity and high insulation. The TLP387 photocouplers operate at -55ºC to 110ºC temperature range. These TLP387 photocouplers are suitable for 100VDC output modules of programmable controllers, I/O interface boards, and home electric appliances.