To inspire ambient light sensor design and address these issues, this paper proposes a high sample per second, wide dynamic range and ultralow illuminance detection single photon avalanche diode array system on chip. A 16×16 SPAD array architecture along with counter and charge-pump is fabricated in 180nm BCD process and demonstrates 100μlux ambient light sensing@660nm. On-chip FFT processor of 2048 points with 32bit accuracy can process sampled optical waveform for flicker detection. An area-efficient integrated charge pump generates regulated high-voltage (19~25V) to SPADs with on-chip digital auto gain control, which verifies the improvement of optical DR from 87db to 123db.