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BQ25120A: Input quiet time for Ship Mode transition

Johannes Brecher
Prodigy 110 points
Part Number: BQ25120A
Other Parts Discussed in Thread: BQ25121,

Hello,

the datasheet states in the Section "9.3.1.1 Ship Mode Entry and Exit" that there is a period tquiet in which the conditions

  • CDn=High
  • MRn=High
  • Vin<Vuvlo

must remain unchanged.

In my opinion it is not possible to guarantee that there are no changes on the lines MRn and Vin, since the user can press the push button (that is connected to MRn) at any time, as well as connect a charger (which would make Vin>Vuvlo) at any time.

Since there was a problem with the BQ25121 I am now wondering what would happen, if one of these conditions would be violated during the time tquiet.

Would the BQ25120A simply not enter the shipping mode? (In this case would it help to just resend the I2C command to enter the Ship Mode?)

Would there be a different problem? (The datasheet only states "proper operation" but not what would be the result of a violation of this condition)

Best regards,

Johannes

  • 0
    TI__Mastermind 21590 points

    Johannes,
    To enter shipmode, all these requirements need to be met. The tquiet time is maximum 1ms which is much smaller than the time it'll take the user to press the push button and connect a charger at the same time. If any of these conditions are violated during tquiet, the device will simply not go into shipmode and you can resend the I2C command to enter ship mode.
    Regards,
    Raheem