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TLC555-Q1: two near 50% duty signal

Koji Ikeda
Expert 5705 points
Part Number: TLC555-Q1
Other Parts Discussed in Thread: TLC555

Hello support team,

Customer inquires if TLC555 can achieve the following signal generation. 

If TLC555 can achieve this, could you show how to use TLC555? Rough schematic is very helpful to understand.

Thanks,

Koji Ikeda

  • Former Member
    0 Former Member

    Hello Ikeda-san,

    This resource will provide you an explanation of how to get a 50-50 duty cycle from you timer along with a schematic.

    Please note, the output waveform is not an ideal vertical line due to the charge and discharge cycles of a capacitor.  If you require the waveform to look as shown above, one possible solution is to use a 555 timer with a simple comparator.

    Please let me know if you need further assistance.

    Regards,

    Daniel

  • 0 in reply to Former Member
    TI__Expert 5705 points

    Hello Daniel-san,

    Thank you for your support. I'm not sure what 555 with comparator can achieve. Could you show rough schematic?

    Thanks,

    Koji Ikeda

  • Former Member
    0 Former Member in reply to Koji Ikeda

    Hello Ikeda-san,

    What about something like this?  The "Ref" signal would just be a DC mid-supply.  I would think the main concern would be the comparator input loading the output of the TLC555.

    Regards,

    Daniel Miller

  • 0 in reply to Former Member
    TI__Expert 5705 points

    Hello Daniel-san,

    Thank you very much for your support.

    That's good idea, however, in this case, second signal duty would vary with each reference, they need around 50% on signal 2 as well. Do you have any good idea to support their requirement.

    Thanks,

    Koji Ikeda

  • Former Member
    0 Former Member in reply to Koji Ikeda

    Hello Ikeda-san,

    My apologies.  I missed that you need two signals.

    In such a case, I think you have two options.

    Option 1: Use two comparators.  The first comparator uses the "Ref" voltage at In+ and the output of the 555 timer at In-.  The second comparator uses the "Ref" voltage at In- and the output of the 555 timer at In+.

    Option 2: Use a comparator as shown above and an inverter to generate the second signal from the output of the comparator.

    Please let me know if I have sufficiently answered your question.

    Regards,

    Daniel Miller