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TPL5010: Need assistance in using TPL1050

Danilo A.
Mastermind 34570 points

Part Number: TPL5010

Hi Team,

Posting on behalf of our customer.

I'll share this E2E post with our customer so he can reply when needed.

We are experiencing an issue with the TPL5010 watchdog timer and would appreciate any assistance.
  • The processor sends a pulse train after a 150‑second initialization period; no pulses are present at the DONE pin (pin 4) during initialization.
  • The timer resistor is 43 kΩ, giving an interval of approximately 300 seconds.
  • After 150 seconds, the TPL5010 is continuously reset by the pulse train.
  • The WAKE pin (pin 5) is not used.
  • If the DONE signal stops, we expect RST (pin 6) to go low after 300 seconds, disabling the regulator and dropping the 5 V output to 0 V.
  • However, we cannot get pin 6 (RST) to go low under any condition.
Any feedback would be appreciated.

Regards,

Danilo

  • 0
    TI__Guru** 121240 points

    Hi Danilo,

    Were you saying that you were keeping the RST pin HIGH using a 2.5Hz DONE signal and when you want the RST to assert LOW, you stop providing the DONE signal?

  • 0
    Prodigy 50 points

    Hello Noel, thank you for your kind response. RTS is normally high. After power is applied R92 (timing resistor = 43K) for a delay of 300 seconds. However, 150 seconds later, the processor is booted and start sending 2.5 Hz square-wave signal to DONE pin. This is supposed to reset the 300 sec timer internally to TPL5010. It does not. 

    If processor stops operating, no 2.5 Hz signal will be generated and after a start of new 300 seconds time delay. At the end of this time delay, RTS to pull down regulator (AP64350) ENABLE pin low and turns +5 VDC off, hence shuts down the +5 VDC to the processor. 

    I hope what I wrote is clear and understandable. Thank you so much for your help.

  • 0 in reply to Baha Erturk
    TI__Guru** 121240 points

    Hi Baha,

    I see two issues here.

    First of all, TPL5010 is a watchdog timer, it expects a DONE signal in response to the WAKE signal. If we ignore the WAKE signal but provide an asynchronous DONE signal to the TPL device, there is a possibility that RST will assert at some time. We have seen a couple of customers having similar issue.

    Secondly, pin 3 of the TPL device is used to determine the time interval. After Vcc power up, there is current flowing through the shunt resistor to setup voltage for the TPL device to determine time interval. To get a better accuracy, pin 3 should only connect to a shunt resistor. In your schematic, you should remove C35.

    In addition, RST pin is an open-drain output, an external pull-up resistor is required. 

    You can keep using TPL5010, but instead of sending asynchronous 2.5Hz keep-alive DONE signal, send the DONE signal only after receiving the WAKE signal.

  • 0 in reply to Noel Fung
    Prodigy 50 points

    Hello Noel,

    Thank you for your response.  Removed C35 and C38 and WAKE signal is disconnected from the processor. 2.5 Hz heart beat signal is disconnected from the DONE pin. Changed the R92 to 10K to get response quickly instead of 300 seconds. 

    TPL5010 works as follows:

    Every few seconds (5-6 sec) RTS pin goes low for 300 msec and goes high again. This repeats continuously. Note; the processor is removed and 5010 is working buy itself. 5010 does not receive DONE and RST goes low.

    Great, this is what we want. We do not see WAKE signal at all no matter what we do on 2-3 different boards.  

    Upon power application the normal operation has to start for us - delay of 180 to higher number of seconds for the embeded board to initialize and booth itself. If for any reason it stops working due to any possible reason, it has to recover by removing 5VDC turned off and back on. Not able to with train of pulses and no WAKE signal.

    Would you please find out - if you can - why WAKE stops and yet timer keeps going. 

    Much appreciate any feedback or thoughts. THANK YOU NOEL. 
     

  • 0 in reply to Baha Erturk
    TI__Guru** 121240 points

    HI Baha,

    After resistance reading is complete, if there is no DONE signal, there is no WAKE signal. RSTn will toggle every tIP.