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use of TLC5951

Richard Bland
Expert 2050 points
Other Parts Discussed in Thread: TLC5951, TLC5947, TLC5946

I have been evaluating the TLC5946 and TLC5947 and have successfully driven an rgb led with both. I am now considering the TLC5951 as it appears to be cheaper and offers more functionality, and I have some questions.

Why would you want separate clocks for r g and b? Can I connect them together?

Can you use the chip without connecting the DC bus? (too many wires already)

Other articles on this forum refer to needing 3 serial ports to drive this chip - GS bus, DC bus, what's the 3rd?

thanks

Richard

  • 0
    TI__Intellectual 955 points

     Hello Richard,

     We separated GSCLK for R/G/B because we wanted to apply different gamma correction for R/G/B LED lamp using grayscale clock. 

    Yes, you can connect them together.

    Also you can control TLC5951 even if  DC port is not used. But please connect DCSIN and DCSCK pin to GND in that case.

    I'm sorry that I don't know about 3 serial port.

    Best regards,

     Kazuya Nakai.

     

      

     

  • 0 in reply to Kazuya Nakai
    Expert 2050 points

    Thanks Kazuya, that's exactly what I needed to know.

    Richard.

  • 0 in reply to Kazuya Nakai
    Prodigy 250 points
    Hi Kazuya,

    I am using only one TLC5951 device and I am using this device to drive 20 LEDs individually with the dot correction feature.

    Unfortunately, I have some uncertainties after I read through the datasheet as the following:
    1. In the data sheet, the typical application circuit connects the GSSCK, GSLAT, DCSIN, DCSCK, XBLNK, GSCKR, GSCKG and GSCKB altogether, is that mean all these pins follow the CLK you input?
    2. Refer to your comment above, can I still use the DC (dot correction feature) if I connect the DCSIN and DCSCK pins to GND, then use only the GS port to input my CLK and data?
    3. What if I connect XBLNK to the GND all the time? What kind of feature will not be working?

    At the moment, my thought is to use the GSSIN for data input, GSCLK for the clk, GSLAT for the latch control and XBLNK for the PWM enable/disable. Then connect DCSIN and DCCLK to the GND, also the GSCKR, GSCKG and GSSKB to the GSCLK altogether. Will this works? Please kindly comment.

    Thank you,
    Gilbert
  • 0 in reply to Gilbert Liu
    TI__Expert 3275 points
    Hi Gilbert,

    For your question:
    1. Yes, it's a little confusing. Acutally these pins are connected seperately, not tie togther. In the real application, you can tie GSCKR/G/B together.
    2. Yes, you can tie DCSIN/DCSCK pin to GND, only use GS port for CLK and Data.
    3. XBLANK is used like enable; if XBLANK is low, the output will be disable, if XBLANK is high, OUTx is enabled.

    Best regards,
    Feifei
  • 0 in reply to Feifei Shen
    Prodigy 250 points

    Hi Feifei,

    Thanks for your reply.

    Greatly appreciated.

    Best Regards,

    Gilbert