In this letter, we report the design of a low-power event-based vision sensor (EVS) digital pixel in a 3D-stacked 45-nm backside illumination CMOS process. The design uses in-pixel analog-to-digital converters and memory to store digitized light intensities. By using a bit comparator to compare digital intensity values of the same pixel in the time domain, the high-fidelity event stream and intensity information from the same pixel can be generated simultaneously. The power consumption of the proposed digital EVS pixel can be as low as 10 nW/pixel. The EVS sensor can achieve a maximum event rate of 260 Meps.