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TLC5926: Use TLC5926 to turn on LED sequentially

Jonathan He
Prodigy 20 points
Part Number: TLC5926
Other Parts Discussed in Thread: SN74HC595, TLC59283

Hi,

I would like to use TLC5926 or similar part to turn on a group of LEDs in a sequential way (meaning turn on first LED for 100us, then turn it off and then at the same time turn on second LED for 100us, then turn it off and then at the same time turn on third LED for 100us, .... and so on).  

My questions are:

(1) Can TLC5926 do this?

(2) If so, how should I set all input signals?  LE always high? OE always low? And can I daisy chain multiple TLC5926 (SDO -> next SDI) to drive more than 16 LEDs?

(3) If not, could you recommend other components to implement this function?  (The reason I prefer to use LED driver IC is that I can have constant current driving, rather than using shifter register IC for constant voltage driving).

Thank you.

Jonathan

  • 0
    TI__Genius 15525 points

    Hi Jonathan,

    Please refer below comments

    (1) Can TLC5926 do this?

    Yes, I think TLC5926 can do this function.

    (2) If so, how should I set all input signals?  LE always high? OE always low? And can I daisy chain multiple TLC5926 (SDO -> next SDI) to drive more than 16 LEDs?

    You only need to send the command once you want to switch the LEDs. As for the LE and OE signals, I think you can refer the below figure. You can regard BLANK as OE signal and LAT as LE signal.

  • 0
    Prodigy 20 points

    Hi, Jared,

    Thanks for your reply.  However, what I actually mean is that can TLC5926 works same as SN74HC595, so that I can set the CLK to 10KHz for example (100us per cycle) and send one clock cycle width pulse to SDI, and keep LE always high and OE always low? If I do this, can I get the waveform in the top post? I don't have time to buy samples to test and the datasheet seems not very clear on this. That is why I ask.  I just want to know whether TLC5926 works the same way as SN74HC595? 

    Thank you.

    Regards,

    Jonathan

  • 0 in reply to Jonathan He
    TI__Genius 15525 points

    Hi Jonathan,

    I got you, please give me some time to test it since I have never used this condition before. I will get back to you when I got the results.

    BR, Jared

  • +1 in reply to Jared Zhou
    TI__Genius 15525 points

    Hi Jonathan,

    I did a test on TLC59283 in the condition as you said (keep LE always high and OE always low) since I didn't have TLC5926 on my hand and I found it could be work. So, I think TLC5926 will be work in this condition.

    As for the waveform in the top, based on your description, I think TLC5926 doesn't work the same way as SN74C595. Because if you want to follow the time sequence as 100us to switching a LED output, I think you can't set the SCLK frequency as 10KHz either. If you increase the SCLK frequency, I think you can easily get the time sequence of LED you attached on the top.

    BR, Jared

  • 0 in reply to Jared Zhou
    Prodigy 20 points

    Hi, Jared,

    Thanks for taking the time to test it. Although I do not completely understand about SCLK frequency in your reply, I will keep keep both options in my design.

    Regards,

    Jonathan

  • 0 in reply to Jonathan He
    TI__Genius 15525 points

    Hi Jonathan,

    Glad to help you!

    BR, Jared