| 摘要 |
<p>A method and device for lowering the Electro-Magnetic Interference (EMI) of a Pulse Width Modulation (PWM) dimming circuit is disclosed in this invention. The method includes the following steps: the frequency variation range of a PWM dimming control signal is set; the PWM dimming control signal is controlled so as to vary periodically in the frequency variation range. In this way, a light emitting diode (LED) driver operates in the frequency jitter mode of a PWM dimming state; if the EMI is relatively serious at a certain frequency point, the frequency of the PWM dimming control signal varies in a certain range which includes said frequency point, thereby the EMI that concentrates at said frequency point being de-concentrated beside said frequency point, and thus the LED driver is enabled to reach to an EMI standard.</p> |
