The PC817 is a low-cost, high-gain, and high-speed optocoupler (also known as an optoisolator) integrated circuit (IC) that is widely used in electronic circuits. It is manufactured by multiple manufacturers such as Sharp and Everlight.
The PC817 consists of an infrared emitting diode (IRED) optically coupled to a phototransistor. The IRED emits infrared light that is modulated by an input signal, and the phototransistor responds to the modulated light and produces an output signal that is proportional to the input signal. The optocoupler provides electrical isolation between the input and output signals, which makes it useful for many applications where noise, high voltages, or ground loops can be a problem.
The PC817 is commonly used in power supplies, motor control circuits, digital and analog signal isolation, and other applications that require signal isolation or voltage level shifting. It is available in a variety of packages, including the standard 4-pin DIP (dual in-line package) and surface mount packages, making it easy to integrate into a wide range of electronic designs.
The PC817 has a high isolation voltage, typically 2.5kVrms, which provides a high level of safety in applications that require isolation. It also has a fast switching speed, typically 18μs, which makes it suitable for high-speed digital and analog signal isolation applications.
Overall, the PC817 is a versatile and widely used optocoupler that provides a cost-effective solution for a variety of applications that require signal isolation or voltage level shifting.