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TPS65217: Use battery can not power on the system

Part Number: TPS65217
Other Parts Discussed in Thread: AM3352, ,

Dears,

When used TPS65217C+AM3352 for system design, TPS65217C used battery for power input, and can not power up , Vsys have no output. When I use AC or USB for input, it can be normally power up, why could cause this? 

  • Hi Abner,

    Thread has been assigned to the expert of this device.

    Best regards,
    Jari Niemelä
  • Abner,

    When BAT is the only power supply for the system, the TPS65217 requires a falling edge on the PB_IN pin to begin the power-on sequence.

    On the TPS65217CEVM, this is a physical push-button that you can press after applying the battery voltage.
  • Brian,

    Thank you for your advise, and I find a file figure 50ms at least on PB_IN at low status, how long is the max time at low status on PB-IN? Is there have an clear definition?
  • Abner,

    The max time that PB_IN can go low for is based on when when PB_IN generates a Reset, which is 8 seconds long. If PB_IN is held low continuously, the TPS65217 will reset every 8 seconds.

    An alternative to using a physical push-button would be routing the PGOOD output signal to the PB_IN input pin.
  • Dear Brian,

    But when I used >1.5s low level on PB_IN , TPS65217 could not normally start, what's the reason cause this?
  • Abner,

    Are you holding the PB_IN pin low before the battery is connected to the BAT pin? If so, you may need to wait until after the battery is connected, because the PB_IN pin says it needs a hi-to-low edge on the PB_IN pin.

    What is the voltage on the BAT pin? The BAT voltage needs to be above UVLO (default = 3.3V) to be recognized as a good battery

    Also, did you check to make sure the PWR_EN pin is high? If PWR_EN pin is not high, the TPS65217 will power cycle (power-down, then power-up) every 5 seconds.

    If you are still having issues after checking these items, please attach an oscilloscope screen shot (showing BAT, PB_IN, PWR_EN, and LDO1 voltages) or I cannot debug this issue any further.