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TPL5010: WAKE is toggling sometimes while DONE is tied to GND

Jason Cardwell
Prodigy 90 points
Part Number: TPL5010


Hi,

I am evaluating the TPL5010 for a timing circuit. I can see from the thread here https://e2e.ti.com/support/clocks/f/48/t/549435 that 

"The output pulse on the WAKE pin is only seen if a DONE signal is received from the MCU within the required time period. The WAKE signal is normally low unless otherwise triggered by the receiving of a DONE"

and

"The TPL will not output a WAKE if no DONE input is received. Instead, a periodic RSTn signal will take place." 

Currently my setup has DONE tied to GND via a 10K resistor. The TPL will vary between outputting pulses on the WAKE signal and pulse on RST. It also sometimes does neither, with WAKE sitting low and RST sitting high. The circuit will run outputting RST pulses, then stop outputting them, then may recommence or else start outputting pulses on WAKE. This all happens with no outside influence, a scope probe attached to WAKE, RST and DONE.

I would like to be able to rely on a consistent pulse coming from either WAKE or RST, but it doesn't seem to be happening. I would greatly appreciate advice on how to resolve this issue.

Regards,

Jason

  • 0
    TI__Genius 16845 points
    Hi Jason,

    Can you send me your oscilloscope capture of the WAKE, RSTn, and DONE waveforms? This may shed some light into what is causing the WAKE pulses.

    In my setup I am using the TPL5010EVM powered by a coin cell battery and DONE is pulled to GND via 100K resistor. I observe the periodic pulse on RSTn without pulses on WAKE.

    Kind regards,
    Lane
  • 0 in reply to Lane Boyd
    Prodigy 90 points

    Hi Lane,

    Thanks for your response. Please see some scope grabs attached.

    (1) Yellow - DONE

    (2) Blue - RSTn

    (3) Pink - WAKE

    Here below you can see RSTn working as expected.

    But here below is WAKE toggling while no input exists on DONE.

    Here, WAKE toggling stops and RSTn toggling resumes again with no activity on DONE.

    Here, below WAKE toggling stops and there is no activity on any signal!

    I hope this is useful. I can't quite understand what might be going on.

    Regards,

    Jason

  • 0 in reply to Jason Cardwell
    TI__Genius 16845 points

    Hi Jason,

    Thanks for sharing the waveforms. I need to investigate this issue further. I'm currently working to duplicate this on my bench. In the meantime, I would like to request some additional information:

    • Can you share the schematic? You can send the schematic to clock_support@list.ti.com if you do not wish to share it on the forum.
    • Does the device startup properly? How often is the device operating in the correct mode (RSTn toggling), compared to when WAKE toggles and neither toggles?
    • Oscilloscope capture of the switch from RSTn to WAKE
    • Do you observe this issue on other parts or other boards?

    Kind regards,
    Lane

  • 0 in reply to Lane Boyd
    Prodigy 90 points

    Hi Lane,

    I since built another circuit using a fresh sample and am having better results with it. With no input on DONE (i.e. tied low) I get consistent RSTn pulses.

    The first part I used though is still exhibiting the same problem. I'm using a solderless breadboard with a SOT23-to-DIP adapter board to mount the TLP. On the adapter board is the 100nF cap as in the schematic. The rest of the connections are made on the solderless breadboard. When swapping the SOT23-to-DIP board with one with the new part mounted (and new 100nF cap) the results are better. It makes me inclined to believe I perhaps have a faulty/damaged part, although it was straight out of the packet. 

    See below my schematic and screenshots you requested. The last screenshot is an approx 15 minute capture of the RSTn, WAKE and DONE signals on the original part - to give an idea how often activity exits and changes on each signal.

    Regards,

    Jason

  • 0 in reply to Jason Cardwell
    TI__Genius 16845 points
    HI Jason,

    Thanks for sharing this information. I have looked into this further and combined with your findings, it is most likely that the first part you used is faulty. I can't duplicate the issue here and I don't see any issue with your schematic.

    For now, I'll close the thread. Please let me know if you continue to observe this issue across other parts and we can investigate further.

    Kind regards,
    Lane