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TPS65217: PGOOD High in OFF State

Antonio Fadhel
Genius 9410 points
Part Number: TPS65217

Team,

One of my customers noticed that their TPS65217 PGOOD is HIGH when in the OFF state (battery connected but before wakeup event) on both their board and our EVM. It should be LOW in this case per the datasheet state diagram. Any ideas what can be causing this?

- PGOOD is HIGH in the OFF state when battery is used
- When power is applied to USB input instead of BATT, LDO1 turns ON in the OFF state. This was tested on the eval board setup in the default configuration, connected to the USB-serial module, which was unplugged and plugged back in before powering on. PGOOD is HIGH when USB input is used
- AC input has identical behavior to USB input

I believe the LDO1 turning on is because USB/AC count as wakeup events, but PGOOD should remain LOW either way. Please let me know your thoughts.

Thanks,

Antonio

  • 0
    TI__Genius 10000 points
    Antonio,

    Thank you for reaching out with E2E. I have assigned this question to our application expert on this device. We will look into this and get back to you shortly.

    Thanks,
    Nastasha
  • 0
    TI__Mastermind 30260 points
    For starters, there are 2 PGOOD pins on the TPS65217: PGOOD (pin 26) and LDO_PGOOD (pin 46).

    And you are correct: an edge on either AC or USB is considered a wake-up event. When only the battery is applied, the PMIC is waiting for a Push-Button press (on PB_IN) but when AC/USB is applied the PMIC automatically initiates a power-up sequence. So although the TPS65217 started in the OFF state, it was allowed to transition to the ON state due to the application of USB power.

    As long as the power sequence continues uninterrupted, LDO_PGOOD will go high after Strobe Sequence 3 and PGOOD will go high shortly after Strobe Sequence 5.

    The only thing that would prevent this sequence from occurring is if the PWR_EN is held low by the processor for more than 5 seconds(see Figure 3 on pg 19 of the datasheet).
  • 0 in reply to Brian Berner
    TI__Genius 9410 points

    Hi Brian,

    This is referring to PGOOD (pin 26). The issue is that it is HIGH after battery insertion but before a wakeup event (in OFF state). This should not be the case according to the highlighted states below. The PWR_EN pin is just tied to the battery which I believe still meets the timing requirement if I'm interpreting correctly: "The PWR_EN pin is level-sensitive (opposed to edge-sensitive), and it makes no difference if the pin is asserted before or after the above power-up events. However, the pin must be asserted within 5 seconds of the power-up event; otherwise, the power-down sequence is triggered and the device enters either OFF state."

    Any ideas on what could be causing this?

    Thanks,
    Antonio

  • 0 in reply to Antonio Fadhel
    TI__Mastermind 30260 points
    Antonio,

    Based on my understanding of the issue, the TPS65217 is no longer in the OFF state. As soon as USB or AC is applied, the device has received a Wakeup event, waits 50ms for de-bouncing the input, goes to the WAIT_PWR_EN state, and if PWR_EN is high it transitions to the ON state.

    If you are saying PGOOD is high before AC or USB is applied, this is a different scenario. If this is the case, then the only wakeup event is PB_IN. If the PB_IN pin is low when the battery is applied, this is a wakeup event.

    In order to verify that no wakeup event has occurred, I would need to see an oscilloscope screen shot showing AC/USB, BAT, PB_IN, and PGOOD. You can also monitor PWR_EN and the nWAKEUP output on your end to see if a wakeup event has been detected, then circle back to monitoring AC/USB and PB_IN to find the reason for the event.