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TPL5110EVM: Timer mode with long time - DRV pull up to high itself

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Replies: 4

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Part Number: TPL5110EVM

Hi everyone,

I’m using the TPL5110EVM and for now I’m just testing the accuracy of the component.

I have a problem when I configure a long time for t_ip: the DRV pin jumps to high by itself. In the first figure I have configured the EVM for 5 minutes, so in the figure we can see 3 times the DRV pin jumps to high and I don’t know why. I’m not using a microC, I have just the oscilloscope connected. There isn’t a DONE signal.

Yellow: VDD

Green: DRV

Blue: DONE

Do you have any idea why this happens?

Thank you in advance!

  • Hi Lucas,

    I checked on the bench with an EVM using Tip = 4sec and I am not observing this behavior. The default setting of DRV is HIGH before the first Tip, but I do not measure DRV is HIGH after VDD is removed. 

    I would not expect the DRV pin to be driven to the supply when the device is off, and not for this duration of >1min. 

    Could you share the jumper configuration and power supply configuration? Is the coin cell battery present? Where did you measure the signals on the board? Let me know if you have any other information that could help debug the issue.

    Kind regards,
    Lane

    ____________________________________________________________________________________

    More information Clock and Timing System products: http://www.ti.com/clock-and-timing/overview.html

    Learn more about clocking fundamentals by watching the TI Precision Labs: https://training.ti.com/ti-precision-labs-clocks-and-timing

  • In reply to Lane Boyd:

    Hi Lane,

    Thanks for the quick answer.

    In fact with a small T_ip it's working without problem. The problem is when I configure for more than 1min for example.

    The configurations were: a power supply 2V (limited at 200mA), the coin cell battery is not present. The signals were mesured in the IO pins connected at the osciloscope.

    The timer mode was configured with a jumper and J1 was configured as indicated in the datasheet. I used Rext1 and Rext2 to set the time interval. Here is a photo:

    As mencioned the DRV pin jumps to high by itself. I did another test (below the result) for 5min: in M1, M2 and M3 I pressed the DONE button (S2 in the EVM board) so it's normal the DRV jumps to high,

    but in two other moments it's not normal. In the first one there is a little pulse in DONE signal, less than 1v, maybe this pulse made the DRV go high.

    Best regards,

    Lucas.

  • In reply to Lucas Souza1:

    Hi Lucas,

    Thank you for all of the information.

    I did not try this for time intervals longer than one minute. I can check that next time I return to lab.

    One thing that I notice is that you measure VDD_uC from the header, but this is not the same node as the VDD which supplies the device. You might measure VDD at the VBATT or AUX_VDD test points. I'm interested in how VDD compares to VDD_uC.

    Have you measured how long it takes after turning off power and DRV goes high for DRV to return low?

    Kind regards,
    Lane

    ____________________________________________________________________________________

    More information Clock and Timing System products: http://www.ti.com/clock-and-timing/overview.html

    Learn more about clocking fundamentals by watching the TI Precision Labs: https://training.ti.com/ti-precision-labs-clocks-and-timing

  • In reply to Lane Boyd:

    Hi Lane,

    About VDD and VDD_uC we have the same voltage (in this case 2V).

    I did not measure that time but I think the problem was when I touch the jumper connected to DONE pin.

    I tried with a few seconds and since I was touching the DONE pin there was a noise that made DRV jump to high because it takes as a signal.

    Thank you!

    Best regards,

    Lucas