The TLP523-4(F) is a quad optocoupler from Toshiba's TLP52x series. It is a high-speed, high-sensitivity, logic transfer IC optocoupler with a built-in photo-diode and a signal-isolation IC. It is designed to provide isolation between a signal-source signal line and a load, such as a microprocessor or an ASIC. It features a built-in photo-diode, which is illuminated by the signal being transferred; this in turn generates a photocurrent, which triggers the signal-isolation IC in the optocoupler. The optocoupler provides a very small propagation delay and low saturation voltage, making it well suited for low-power and high-speed applications. It is available in a 4-pin SOP-package; its operating temperature range is -40 to 85 degrees Celsius.