The EL817(A)-F is an optocoupler manufactured by Everlight. It is a DIP-4 device in an RoHS package. The optocoupler is an input/output interface device, used to electrically isolate circuits from each other, helping to protect against voltage spikes and other forms of electrical interference. The EL817(A)-F has a CTR (Current Transfer Ratio) of 50-600%, and an insulation resistance of more than 100MO. It has an operating temperature range of -55°C to 85°C, and a storage temperature range of -55°C to 100°C. It has an on-state current of 1.3mA, and an off-state voltage of 1.2V. It is suitable for applications such as motor speed control, PWM, power supplies, and analog and digital isolators.