This report presents a Circuit Analysis of the STMicroelectronics BBYBRPAA die found inside the VL6180C proximity sensor which contains both a proximity sensor and an ambient light detector. The VL6180C combines an IR emitter, a proximity sensor, and an ALS in a three-in-one, reflowable package. The ports for the IR emitter, ALS, and proximity sensor are arranged in a line on the top surface of the package. The proximity sensor is based on single photon avalanche diode (SPAD) technology, which allows for the detection of a low intensity optical pulse with picosecond jitter accuracy.