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BQ24167: Use only IN input on BQ24167

Alex Antiquera Bomboli
Prodigy 60 points
Part Number: BQ24167

Tool/software:

I'm designing a charger using BQ24167. I'd like to only use the IN input, ignoring the USB-input.

Can I do any of the following:

- Leave USB floating and omit the 1μF capacitor;
- Omit the 4.7μF capacitor on PMIDU;
- Leave USB1, USB2, USB3 floating;

Do you have other recommendations for this scenario?

     Regarding USB1, USB2 and USB3 there are conflicting statements in the datasheet:

                One says: Driving IUSB1, IUSB2, and IUSB3 all high places the bq24167 in High Impedance mode where the buck converter is shutdown regardless if an input is connected to USB or IN.

                Another point in datasheet says: USB1, USB2 and USB3 have no effect on the IN input.

Point 2:

/PG and /CHG are open drain outputs active low, there is no mention about pull up recomendation to connect to a MCU, are externall pull ups required on MCU voltage level to connect to MCU interface?

Point 3:

I am planning to add externall pull-ups from MCU IO level on pins /CE, /PG and /CHG. Is there a current consumption from BQ24167 pins when pull-ups are active and VIN is not present?

  • 0
    TI__Mastermind 26645 points

    Hi Alex, 

    Thank you for reaching out via E2E. Please see my comments below. 

    If you are not to use USB input TI advises to connect USB to GND and place 0.1uF capacitor at PMIDU. IUSB1, IUSB2, and IUSB3 can be left floating. 

    Alex Antiquera Bomboli said:
     Regarding USB1, USB2 and USB3 there are conflicting statements in the datasheet:

    Thank you for pointing out this conflict. The statement that driving all 3 pins high will put the device in high impedance state is accurate. Please ignore the conflicting statement in the pin functions table. We will work to correct that in a future datasheet revision. 

    Point 2:

    As shown in datasheet figure 2 on page 10 /PG and /CHG pins can be connected to DRV pin as pullup. As reference on the BQ24166EVM board /PG and /CHG are pulled up to DRV through a 1.5kohm resistor and LED. If you choose to use it DRV pin bias supply will not be active when VIN is not present. 

    It is recommended to use a 10kohm if connecting to MCU. The logic high threshold (VIH) for /CE, /PG, and /CHG is 1.3V (spec listed on datasheet page 5) and max allowable pullup voltage is 7V. Therefore a typical 1.8V, 3.3V, or 5V pullup rail is acceptable. 

    Point 3:

    Leakage current spec for /CHG and /PG is 1 uA when pulled up to 5V. This is listed on datasheet page 5. Additionally, /PG and /CHG pins are high impedance when no VIN is connected. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Prodigy 60 points

    Thank tou very much Garrett.