Circuit for realizing voltage-self-adaptation PWM (Pulse Width Modulation) light adjustment of LED (Light Emitting Diode) under drive of prepositive constant-current source

Circuit for realizing voltage-self-adaptation PWM (Pulse Width Modulation) light adjustment of LED (Light Emitting Diode) under drive of prepositive constant-current source

  • CN 102,821,526 A
  • Filed: 09/05/2012
  • Published: 12/12/2012
  • Est. Priority Date: 09/05/2012
  • Status: Active Grant
First Claim
Patent Images

1. realize the circuit of LED voltage adaptive PWM light modulation under the constant-current source pre-driver, comprise output loading LED string LED1 and output filter capacitor Co1;

  • It is characterized in that this circuit also comprises the controlled DC current source Is1 of prime, and the PWM adjusting control circuit that joins with output loading LED string LED1;

    Output filter capacitor Co1 is connected in parallel on the two ends of controlled DC current source Is1, output loading LED string LED1 and the two ends that are connected in parallel on controlled DC current source Is1 after the PWM adjusting control circuit is connected;

    The input of dim signal is connected to the control end of controlled DC current source Is1;

    Said PWM adjusting control circuit comprises;

    pulse current source ID1, voltage sampling circuit, voltage control and PWM duty ratio generation circuit that pulsewidth is controlled;

    The anode of pulse current source ID1 is connected to the negative terminal of output loading LED string LED1 and the input of voltage sampling circuit simultaneously, and the output of voltage sampling circuit is as the input of voltage control and PWM duty ratio generation circuit;

    The output signal of voltage control and PWM duty ratio generation circuit is duty ratio D, and the duty cycle signals of this output is connected to the control end of pulse current source ID1.

View all claims
    ×
    ×

    Thank you for your feedback

    ×
    ×