Patent ID: 9613572
Date: 2017-04-04
CPC Classifications: G09G,H05B

Claim:
1. A controller for dimming light-emitting diodes, comprising: a pulse width modulation pin for receiving a pulse width modulation signal generated by a micro-controller; a low-pass filter for generating a direct current signal according to the pulse width modulation signal; a frequency detection unit for generating a logic value according to a threshold and the pulse width modulation signal; and a control signal generation module coupled to the low-pass filter and the frequency detection unit for generating a switch control signal to a first switch connected to the light-emitting diodes in series according to the direct current signal, the logic value, a reference voltage, and the pulse width modulation signal, wherein the first switch is turned on and off according to the switch control signal, wherein the control signal generation module comprises: wherein when a frequency of the pulse width modulation signal is lower than the threshold, the controller enters a digital dimming mode, and when the frequency of the pulse width modulation signal is higher than the threshold, the controller enters an analog dimming mode.