TOSHIBA PHOTOCOUPLER IRED & PHOTO-TRANSISTOR TLP291 TLP291 Power Supplies Programmable Controllers Hybrid ICs Unit: mm TLP291 consists of photo transistor, optically coupled to an infrared emitting diode. TLP291 is housed in the SO4 package, very small and thin coupler. Since TLP291 is guaranteed wide operating temperature (Ta=-55 to 110 ˚C) and high isolation voltage (3750Vrms), it’s suitable for high-density surface mounting applications such as small switching power supplies and programma.