Fully digitalized switch-mode LED driver without ADC

Abstract

A digitalized switch-mode LED driver is implemented using a O.35f.1m high voltage process, which featured by no use of any ADCs. The comparison result between the output current and the desired current causes the counter to increase or decrease its binary value which determines the duty ratio of the PWM signal. This PWM signal controls switching devices. A delay routine added in the counter prevents oscillation of the counter value owing to a high speed clock.