Patent ID: 9743475
Date: 2017-08-22
CPC Classifications: H05B,Y02B

Claim:
1. An operation method for an LED dimming device, comprising: step A: sampling a pulse width modulation signal, and respectively counting a time period when the pulse width modulation signal is at high level and a time period when the pulse width modulation signal is at low level, wherein a first counter of a counter module increases a first counting value when the pulse width modulation signal is at high level and a second counter of the counter module increases a second counting value when the pulse width modulation signal is at low level; step B: determining whether a rising edge of the pulse width modulation signal is detected; step C: calculating a duty cycle of the pulse width modulation signal according to the first counting value and the second counting value stored in the counter module when the rising edge of the pulse width modulation signal is detected; step D: after calculating the duty cycle, resetting the first counting value and the second counting value of the counter module; and step E: driving an LED module according to the duty cycle; wherein in the step C, a duty-cycle calculating unit calculates and obtains the duty cycle by dividing the first counting value by the sum of the first counting value and the second counting value, when the first counting value stored in the first counter is less than the first preset value and the second counting value stored in the second counter is less than the second preset value.