Voltage converting apparatus and sub-harmonic detector thereof

摘要

A voltage converting apparatus and a sub-harmonic detector are disclosed. The sub-harmonic detector includes a pulse eliminating circuit, a counter, and a comparator. The pulse eliminating circuit receives a pulse width modulation (PWM) signal and a reference PWM signal having a same period. The PWM signal and reference PWM signal has a plurality of pulses and reference pulses respectively. The pulse eliminating circuit eliminates at least one part of the pulses which overlap with the reference pulses for generating a processed signal. The counter counts the processed signal and the PWM signal during a time period to obtain first and second counting values. The comparator compares the first and second counting values for detecting whether a sub-harmonic condition happens or not in the PWM signal.

主权项

1. A sub-harmonic detector of a pulse width modulation (PWM) signal for a voltage converting apparatus, comprising:
a pulse eliminating circuit for receiving a reference PWM signal having a same period with the PWM signal and receiving the PWM signal from the voltage converting apparatus, the PWM signal having a plurality of pulses, and the reference PWM signal having a plurality of reference pulses, wherein the pulse eliminating circuit subtracts each of the corresponding reference pulses from each of the pulses and generates a processed signal; a counter for receiving and counting the processed signal and the PWM signal respectively within a time period to obtain a first counting value and a second counting value; and a comparator being coupled to the counter and the comparator comparing the first counting value and the second counting value to detect whether a sub-harmonic condition happens or not in the PWM signal.