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TPL5000: Behaviors without Watchdog feature

Kazuhiko Hirano
Genius 11573 points
Part Number: TPL5000

Hello,

 

Let me confirm TPL5000 behaviors without Watchdog feature.

 

DONE connected to GND:

In this case, TPL sends only RSTn pulses at every time delay elapses, no TCAL and WAKE outputs at all?

 

DONE connected to TCAL:

In this case, RSTn is just once after PGOOD gets high, then WAKE pulses at every time delay elapses.

How about TCAL? TCAL pulses are also at every time delay elapses, or not TCAL pulses at all?

 

Best regards,

 

K.Hirano

  • 0
    TI__Mastermind 28960 points

    Hello Hirano-san,

    Based on my reading of the datasheet, I have the following understanding:

    DONE connected to GND:
    TPL5000 still sends out TCAL pulses. WAKE pulses are never sent out in this mode, because no DONE signal is ever received in the previous delay period. The datasheet says connecting DONE to GND disables the watchdog feature, but arguably it permanently enables the watchdog feature and never kicks the dog, ensuring regular resets.

    DONE connected to TCAL:
    RSTn is just once after PGOOD goes high, then WAKE pulses every time the delay elapses. I agree with your understanding.
    TCAL will go high after WAKE goes high, but since DONE is connected to TCAL, both TCAL and WAKE will be reset immediately after TCAL goes high. This is like case C in datasheet figure 7.

    Regards,

  • 0 in reply to Derek Payne
    TI__Genius 11573 points

    Derek,

     

    Thank you for your response.

     

    Let me confirm some more.

     

    DONE connected to TCAL:

    In this case, the WAKE pulse width is around a half period of the internal oscillator?

    How much is the TCAL pulse width?

    It is almost zero and it looks like a just glitch noise because TCAL gets low as soon as TCAL gets high?

     

    Best regards,

     

    K.Hirano

  • 0 in reply to Kazuhiko Hirano
    TI__Mastermind 28960 points

    Hirano-san,

    I have not tested the TPL5000 before. And based on other E2E questions, I am concerned that the behavior for DONE connected to TCAL may be unexpected.

    I am going to acquire a TPL5000EVM and verify the behavior. I will get back to you when I have confirmed, probably later this week depending on EVM shipping. I want to give you more than just my guess.

    Regards,

  • 0 in reply to Kazuhiko Hirano
    TI__Mastermind 28960 points

    Hello Hirano-san,

    With DONE connected to TCAL:

    • The wake pulse width for my measurement was about 7.56ms.
    • The TCAL/DONE pulse is around 22ns.

    Regards,