LIGHT EMITTING DIODE DRIVER HAVING A LOGIC UNIT FOR GENERATING A FREQUENCY CONTROL SIGNAL

摘要

A light-emitting diode driver includes a power switch, a logic unit and a pulse adjustment signal generator. The power switch is used to control a charging level of a light-emitting diode voltage terminal, and controlled to be turned on or off by a pulse-width modulation signal. The logic unit is coupled to a control terminal of the power switch, and used to generate a frequency control signal. The pulse adjustment signal generator is coupled to the logic unit, and used to generate an operational wave according to the frequency control signal and update the pulse-width modulation signal according to the operational wave. When the duty cycle of the pulse-width modulation signal is smaller than a pulse-width modulation threshold, the operational wave has a first frequency. When the duty cycle of the pulse-width modulation signal is larger than the pulse-width modulation threshold, the operational wave has a second frequency higher than the first frequency.

主权项

1. A light-emitting diode driver comprising:
a power switch configured to control a charging level of a light-emitting diode voltage terminal, and controlled to be turned on or turned off by a pulse-width modulation signal; a logic unit coupled to a control terminal of the power switch, and configured to generate a frequency control signal according to a duty cycle of the pulse-width modulation signal; and a pulse adjustment signal generator coupled to the logic unit, and configured to generate an operational wave according to the frequency control signal and update the pulse-width modulation signal according to the operational wave;wherein the operational wave has a first frequency when the duty cycle of the pulse-width modulation signal is lower than a pulse-width modulation threshold, the operational wave has a second frequency when the duty cycle of the pulse-width modulation signal is not lower than the pulse-width modulation threshold, and the first frequency is lower than the second frequency.