The P0102DN 5AA4 is an NPN Silicon Planar Photo Transistor made by STMicroelectronics. This component uses Silicon as the base semiconductor material and comes in a convenient 4-pin PLCC package. It has a nominal dark current of 50nA and an operating voltage of 10V. The device features a fast switching time and superior optical close-up characteristics. It can be used for a variety of applications, including but not limited to, photo sensors, switches, and relays. The STMicroelectronics P0102DN 5AA4 part is an excellent choice for a wide range of applications that require reliable, long-term operation.