Dimming Control Circuit for LEDs


Posted on Feb 7, 2014

A dimming control circuit generates a dimming control signal for determining brightness of at least one light-emitting diode. The dimming control signal has a plurality of bright-dark cycles, each of which consists of a bright phase and a dark phase. The bright phase starts with an adaptive rising portion. The adaptive rising portion restricts the


Dimming Control Circuit for LEDs
Click here to download the full size of the above Circuit.

brightness of the at least one light-emitting diode to increase gradually from zero. The present invention relates to a dimming control circuit and, more particularly, to a dimming control circuit applied to a drive circuit for driving light-emitting diodes. FIG. 1 is a circuit diagram showing a conventional light-emitting diode drive circuit 10. In the example of FIG. 1, the light-emitting diode drive circuit 10 is implemented by a boost-type switching voltage regulator for converting an input voltage V. sub. in into an output voltage V. sub. out desired for driving one or more series-connected light-emitting diodes LED. In accordance with a current I. sub. L flowing through an inductor L and a feedback voltage V. sub. fb from a resistor R, a switching control circuit 11 generates a fixed-duty pulse drive signal FS for turning on/off a switching transistor Q. The duty ratio of the switching transistor Q determines the proportional relationship between the output voltage V. sub. out and the input voltage V. sub. in. The brightness of the light-emitting diodes LED varies depending on the diode current I. sub. LED flowing through themselves. From FIG. 1 is derived an equation regarding to the diode current I. sub. LED: I. sub. LED=V. sub. fb/R=(V. sub. out-N*V. sub. d)/R, where N is the number of the light-emitting diodes and V. sub. d is a voltage drop of one single conductive light-emitting diode. Since the voltage drop V....




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    LED Voltmeter
    Motor-hour-meter
    6418 Tube RIAA Phono Preamplifier
    simple frequency counter circuit
    Weller WLC100 Electronic Soldering Station Circuit Q4012LPH
    LM318 microphone preamplifier circuit design
    Telephone Status Indicator Circuit
    RF Tester
    Frequency counter Logic schematic
    Motorcycle Alarm No.1 - Construction Guide
    A thirty light water digital control circuit
    Ultrasonic insect repellent circuit



    Top