Adaptive low-power zero-cross comparator for discontinuous current mode operated switching mode power supply

摘要

A time off estimator and an adaptive controller implemented on an integrated circuit to emulate current dependent zero crossing circuitry to permit improved performance of a buck type switching mode power supply. The time off estimator circuit is enhanced by an automatic correction circuit for the timing of a zero crossing where energy to a reference capacitor returns to zero and is turned off awaiting the next cycle where the capacitor is again charged and discharged.

主权项

1. A switching mode power supply (SMPS), comprising:
a) a time off estimator to predict a time when a flow of energy is turned off in a clock cycle; b) a reactive element of the SMPS charged and then discharged; c) an adaptive controller configured to sense overshoot or undershoot of power signal in the reactive element and adjust a reference offset voltage; and d) said reference offset voltage connected to a first input of a compare circuit to establish a turn off setting to avoid power signal spikes caused by a turn off time being too long or energy being terminated too soon caused by the turn off time being too short.