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DLPC4422: How to control r/g/b led with dlpc4422

xiaoxinxin
Prodigy 160 points
Part Number: DLPC4422

Hi everyone,

Are the pins RED_LED_EN,GRN_LED_EN,BLU_LED_EN  keeping high and the pins RED_PWM,GRN_PWM,BLU_PWM control led brightness or turn off .Or are they all pwm waveform when projector is running?





 

  • 0
    TI__Intellectual 2245 points

    Hello,

    Thank you for using the DLP E2E forums. 

    I don't quite understand your question that you are asking but i'm assuming you'd like more information on the SSI PWM signals?

    The SSI PWM signals are composed of two sets of control signals, the Enable and PWM signals. 
    The Enable signals denote when the corresponding color (RGB) is turned on (high) and off (low). These are controlled by the color sequences of the controller.
    The PWM signals are meant to control the brightness of the LED. The higher the duty cycle of the PWM signal, the brighter the LED.

    Was there something specific you wanted to know more about?

    Regards,
    Oscar

  • 0 in reply to Oscar Guevara
    Prodigy 160 points

    Yes,but i connect DLPC4422 the Enable signals to each led power chip enable pins,however the power chip is not work.I think that the Enable signals are also similar to PWM sigal.The power chip  enable pin doesn't work with so high-speed signal.  How can I solve it? 

  • 0 in reply to xiaoxinxin
    TI__Intellectual 2245 points

    Hello,

    The enable signals are essentially square waves but they are not the same as the PWM signals. Below you will see how 1 frame in a DLP system is composed of multiple RGB segments. Each color segment you see in the image would translate to a "high" for the corresponding color enable.

    The sequences are embedded within the controller and are not configurable using the DLPC4422 GUI 1.0

    If the enables signals are too fast for your current driver, then our recommendation is to get a driver more suitable for this type of application. 

    Here is a link to a TI reference design of a LED driver for DLP applications. This may provide more useful information.

    Regards,
    Oscar

  • 0 in reply to Oscar Guevara
    Prodigy 160 points

    Should  B_EN  connect dlpc4422 bule_en pin ?  Why it is not used ?how connect this interface to dlpc4422 pins

  • 0 in reply to xiaoxinxin
    TI__Intellectual 2245 points

    Hello,

    In the schematic, U9 is a 6 pin header that was intended to allow for easy measurements and also to allow the user to easily open/close the connections between the control signals and the driver.

    You only need a jumper over pins 5 & 6 to connect the enable signals to the driver SDIM input.
    Same thing applies to Pins 1 and 2. Placing a jumper will ensure the driver is turned off when the other channels are on.

    Thank you,
    Oscar