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TLC59401: About GS register

Guru 21045 points
Part Number: TLC59401

Hi Team,

 

Our customer would like use Grayscale PWM function so they set GS Register value.

After that, they control ON/OFF of LED by the BLANK pin.

We understand that if BLANK pin is high, GS counter is reset but GS Register isn’t reset.

Therefore, we understand that they haven’t to re-set the GS register if they use same brightness of LED after BLANK pin is toggled.

Is my understanding correct?

 

Regards,

Kanemaru

  • Hi Team,

     

    Would you tell me about the progress on this matter?

    I’d greatly appreciate your verification.

     

    Regards,

    Kanemaru

  • Hi, Kanemaru,

    Sorry for the delay.

    Correct and you can refer to the following chapter in datasheet for more details:
    "OUTPUT ENABLE
    All OUTn channels of the TLC59401 can be switched off with one signal. When BLANK is set high, all OUTn
    channels are disabled, regardless of logic operations of the device. The grayscale counter is also reset. When
    BLANK is set low, all OUTn channels work under normal conditions. If BLANK goes low and then back high
    again in less than 300 ns, all outputs programmed to turn on do so for either the programmed number of
    grayscale clocks or the length of time that the BLANK signal was low, whichever is lower. For example, if all
    outputs are programmed to turn on for 1 ms, but the BLANK signal is only low for 200 ns, all outputs turn on for
    200 ns even though some outputs are turning on after the BLANK signal has already gone high."

    Thanks.

    Regards,
    Kenneth
  • Hi Kenneth-san,

    Thank you for the information.

    I understand. Thank you very much.

    Regards,

    Kanemaru

  • Hi Kenneth-san,

     

    I have one more question.

    Our customer would like to control LED ON/OFF sequence by BLANK pin only.

    And, they guess that they can control LED ON/OFF at the following timing chart.

    Could you please let us know if you have any concern?


     

    Regards,

    Kanemaru

  • Hi, Kanemaru-san,

    There's one concern.

    You can refer to following figure:

    After BLANK changes from high to low, OUT will be ON for expected GS duty cycle only when GSCLK number is higher than 4096. That means at customer application, if they use GS<100, OUT will be ON for GS CLKs during 100 CLK, but if GS>100, then for 100 CLK ON period, OUT will be always ON and changing GS won't change the brightness.

    Thanks.

    Regards,

    Kenneth

  • Hi Kenneth-san,

    Thank you for the detail information.

    I understand. Thank you very much.

    Regards,

    Kanemaru