• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 614 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LP5009: Change each(9ch) monochromatic LED brightness individually

Kazuki Kitajima
Intellectual 1480 points
Part Number: LP5009

Hello team,

I'd like to confirm this device use case. The customer tries to use this device for 9 individual monochromatic LEDs.

Is it possible to change each LED brightness individually?

In DS page 22, there are only 4 resistors for brightness(RGB as one resistor?) and I'm assuming it might be difficult to change each LED's brightness.

Thank you,

Kazuki Kitajima

  • 0
    TI__Genius 11836 points

    Hi Kazuki,

        Actually, the brightness of each LED corresponding to each channel depends on the product obtained by multiplying the color-mixing register value (Outx_color) by the related intensity-control register value (LEDx_Brightness). The Outx_color can be different for each monochromatic LED.

        

  • 0 in reply to Charles-Chen
    TI__Intellectual 1480 points

    Hi Charles-san,

    Thank you for answering this. In short, The brightness = (Outx_color)*(LEDx_brightness). There are only 3(4) LEDx_brightness resistors. However, there are 9(12) Outx_color resistors. Therefore each monochromatic LED's brightness can be defined individually.

    Is my understanding correct?

    If this is correct, could you tell me how to calculate brightness? (brightness resistor shows the intensity as %)

    For instance,

    1)Out1_color = 80h(50% mixing), LED0_brightness = FFh(100% intensity) vs 2)Out1_color = FFh(0% mixing), LED0_brightness = FFh(100% intensity).

    Thank you,

    Kazuki Kitajima

  • 0 in reply to Kazuki Kitajima
    TI__Genius 11836 points

    Hi Kazuki,

    Thank you for answering this. In short, The brightness = (Outx_color)*(LEDx_brightness). There are only 3(4) LEDx_brightness resistors. However, there are 9(12) Outx_color resistors. Therefore each monochromatic LED's brightness can be defined individually.

    Is my understanding correct?

    Yes.

    If this is correct, could you tell me how to calculate brightness? (brightness resistor shows the intensity as %)

    For instance,

    1)Out1_color = 80h(50% mixing), LED0_brightness = FFh(100% intensity) vs 2)Out1_color = FFh(0% mixing), LED0_brightness = FFh(100% intensity).

    I can't understand what you mean. Can you clarify your requirement more clearly? If you use monochromatic LED, you don't have to pay attention to color mixing.

     

     

       

  • 0 in reply to Charles-Chen
    TI__Intellectual 1480 points

    Hi Charle-san,

    For the second question, the customer wants to change each monochromatic brightness.

    In this case, they have to use the Outx_color to change brightness because the LEDx_brightness isn't independent for each channel and the brightness can be related to (Outx_color)*(LEDx_brightness).

    Is there any index like % in LEDx_brightness to control the brightness by changing the Outx_color?

    Thank you,

    Kazuki Kitajima

  • 0 in reply to Kazuki Kitajima
    TI__Genius 11836 points

    Hi Kazuki,

        In this case, they have to use the Outx_color to change brightness because the LEDx_brightness isn't independent for each channel and the brightness can be related to (Outx_color)*(LEDx_brightness).

        Yes. The brightness of each monochromatic LED is related to the LEDx_brightness. If the LEDx_brightness is fixed, the % in LEDx_brightness equals to Outx_color/(0xFFh) * 100%.

       

  • 0 in reply to Charles-Chen
    TI__Intellectual 1480 points

    Hi Charles-san,

    Thank you! Now it's clear.

    If I have any other questions, I'm going to ask your team again. 

    Best Regards,

    Kazuki Kitajima