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TPL5111: Fix pulse width 100ms on DRV and 5s interval

Erik de Wit
Prodigy 45 points
Part Number: TPL5111

Hello,

I want to use the TPL5111 as a common but ultra low power timer like a 555. I want the DRV pin to be high for ~100ms every ~5s. I was thinking of using a resistor and capacitor to drive the DONE pin ~100ms after the DRV pin is set high. Is this possible?

Also, is there a spice model for the TPL555?

Many thanks

  • 0
    TI__Expert 8865 points
    Hi
    I have notified the engineer to respond. Thanks for having patience.
    Best regards
    Puneet
  • 0 in reply to Puneet Sareen
    Prodigy 45 points

    Thank you Puneet, hope to hear from him/her soon. I have a RC-transistor circuit in sim that could do it, but I think its better when its RC only.

  • 0 in reply to Erik de Wit
    TI__Prodigy 165 points

    Yes, this is feasible. While DRV is active, if the DONE signal input goes high (> 0.7 VDD for at least 100ns) -> DRV output will go low/OFF.

    Usually DONE signal is provided by MCU : Its an indication of finished (DONE) executing all the tasks after a waking-up (now I am ready to go to sleep).

    Tina has 555 simulation models.

    Regards,
    Siva.

  • 0 in reply to Siva RaghuRam
    Prodigy 45 points

    Hi Siva,

    Thank you for your reply. I can't use the normal 555 series due to battery life. My question is actually if you could provide me the calculation or advice values in order to do this with RC only, without using transistors. 

    I was thinking about using it like below but I don't know the DONE input circuit and characteristics and the DRV output circuit and characteristics to know if I will face any problems with a circuit this simple. And, I don't know how much deviation there is in these characteristics due to production variables and ambient temperature.

  • 0 in reply to Erik de Wit
    TI__Prodigy 165 points

    Thanks Erik,

    The base current for Q1 will be almost 4mA (assuming VBE of ~1V). Do you really need to drive a transistor & charge 10uF cap for your battery operated solution?
    Typically TPL devices drive a small FET or Enable input of a LDO/DC-DC converter to switch on the power. Lets take this discussion off-line to get to know more details about your requirements.

    Regards,
    Siva.

  • 0 in reply to Siva RaghuRam
    Prodigy 45 points

    Hi Siva,

    Thanks, I managed to get a 100ms pulse every 5s with the schematic below, it workes great and has a total Iq (including LDO) of 2,5uA: