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BQ25790: 3.3V Pull-Up Rail

Logan Wood
Prodigy 50 points
Part Number: BQ25790

Hello,

We are planning to use the BQ25790 in our design as the first regulator in the power scheme. In the evaluation board design, the board has an external LDO (U2 --> TLV76033DBZR) tied to the inputs (VBUS/BAT), it is used for the host controls and status pin. In our application, this ICs SYS output will go directly to another switcher that is set to 3.3V. Trying to cut as much cost as possible so was curious if we could use this as our 3.3V pull-up rail instead of this additional LDO? I want to make sure there will be no power sequencing issues if this approach is taken.

The picture below highlights above.

Thanks.

  • 0
    TI__Guru**** 166606 points

    Hi LDO,

    As long as there is a battery in your system so that the 3.3V pull up is present, I see no issue.  If, however, you plan to operate without a battery, there will be a delay between VBUS applied and VSYS up to power the 3.3V buck converter.  Unless you are using the pull up to disable charge at power up or for SDA/SCL or make some decision passed on /PG, I do not see an issue.

    Regards,

    Jeff