FODM8801 OptoHiT™ Phototransistors onsemi FODM8801 OptoHiT™ Phototransistors are first-of-their-kind phototransistors, utilizing a leading-edge, proprietary process technology to achieve high operating temperature characteristics up to +125°C. The optocoupler consists of an aluminum gallium arsenide (AlGaAs) infrared light emitting diode (LED) optically coupled to a phototransistor, in a compact half pitch, mini-flat, 4-pin package. It delivers high current transfer ratio at very low input current. The input-output isolation voltage, VISO, is rated at 3750 VACRMS. onsemi FODM8801 devices are ideally suited for use in DC-DC converters.