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TPL5010: The watchdog RSTn open drain output fails after few month in operation

Ronald Ruizenaar
Prodigy 150 points
Part Number: TPL5010
Other Parts Discussed in Thread: STRIKE

We use the TPL5010 in a 4G modem for outdoor operation. The RSTn signal has an pull up (47k) and is connected to the reset of a MSP430 controller. The RSTn open drain output should be in high impedance state in normal operation. After a few months we found that some of our products are kept in reset continuously (RSTn of the TPL5010 is constant low). A powercycle does not help anymore and the chip looks broken! After investigation we found that the TPL5010 was working well except for the RSTn output! We still see the WAKE pulse! The high impedance state of the RSTn however was not high impedance anymore, but around 1k to 50k! We have investigated about 20 devices with the same problem.

I only can think of the following:

  • Humidity: The pcb has no conformal coating as protection again humidity, however no damage was found on other components.
  • ESD: The RSTn pin is also used to program the MSP (SPI-BY-WIRE connection). The pin does not have extra ESD protection.

I need some advice to find the cause of this problem. At this moment 20 out of 500 products have this issue!

Thanks in advance,

Ronald

  • 0
    TI__Genius 16845 points

    Hi Ronald,

    Thanks for posting on E2E. We haven't seen this issue before, but we'll try to help resolve this issue.

    Could you share the schematic? If you prefer not to share on the public forum, you could share it with me in a direct message.

    Have you tried an ABA swap test? This can help confirm it is indeed a device issue and also help identify system issues.

    Kind regards,
    Lane

  • 0 in reply to Lane Boyd
    Prodigy 150 points

    Hi Lane,

    Thanks for your reply! Yes, we did the ABA test. The issue moves with the component!

    This is the part of the schematic. When I measure the voltage on pin 1 (J5) I got values between 0.08 to 1.6V over 20 failed devices (per device the voltage value does not change much).

    It is a multi-layer board (4 layers) with one inner layer for ground only. The system is battery powered (3.6V lithium) and the 3.3Volt power supply for this circuit works fine!

    Best regards,

    Ronald 

  • 0 in reply to Ronald Ruizenaar
    TI__Genius 16845 points

    Hi Ronald,

    Thank you for confirming. We have not seen this issue before and i can only speculate on the cause of the failure.

    Based on the information you have provided, I suspect the most likely cause of failure is ESD. The external header on the RSTn pin allows another avenue for ESD to strike. Is it possible to add ESD protection circuitry?

    Perhaps a device can be sent to a test lab for further analysis to determine if the failure mode is congruent with this assumption

    Kind regards,
    Lane

  • 0 in reply to Lane Boyd
    Prodigy 150 points

    Hi Lane,

    Thanks for your expertise! I have several components with this issue (removed from the board). Is there any other way to find out if ESD is the problem?

    Thanks again,

    Ronald

  • 0 in reply to Ronald Ruizenaar
    TI__Genius 16845 points

    Hi Ronald,

    Unfortunately I cannot think of another way to confirm it. Visual inspection is the first step and sometimes visual damage can indicate it, and you have done the necessary debugging. I wish I could help resolve your problem but I hope this information helps. 

    Kind regards,
    Lane