High-Speed Transistor Optocouplers

onsemi High-Speed Transistor Optocouplers consist of an AIGaAs LED optically coupled to a high speed photodetector transistor. A separate connection for the bias of the photodiode improves the speed by several orders of magnitude over conventional phototransistor optocouplers by reducing the base-collector capacitance of the input transistor. The onsemi  HCPL4503M has no internal connection to the phototransistor for improved noise immunity. An internal noise shield provides superior common mode rejection of up to 50,000V/µs.