TLPxxx InGaAs Infrared LED & Photo Transistors Toshiba's TLPxxx InGaAs Infrared LED & Photo Transistors consist of photo transistors optically coupled with InGaAs or GaAs infrared emitting diodes. They are guaranteed a wide operating temperature (Ta = -55 to 125 ̊C ) and high isolation voltage (3750Vrms). They are suitable for switching power supplies and hybrid ICs and for high-density surface mounting applications such as programmable controllers.