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BQ25606: SYS output condition

Jay Yeh
Intellectual 465 points
Part Number: BQ25606

Hi

I am not sure if my understanding is correct. In the BQ25606 datasheet, section 10:

In order to provide an output voltage on SYS, the BQ25606 device requires a power supply between 3.9 V and 13.5 V input with at least 100-mA current rating connected to VBUS and a single-cell Li-Ion battery with voltage > VBATUVLO connected to BAT. The source current rating needs to be at least 3 A in order for the buck converter of the charger to provide maximum output power to SYS.

Does it means that both VBUS and VBat need to be exist to have the output on Vsys?

Thanks a lot.

  • 0
    TI__Guru 57651 points

    Hi,

    No, the charger works when VBUS or VBAT is present. Please refer to 8.3.1 Device Power Up from Battery without Input Source and 8.3.2 Power Up from Input Source on the d/s. Please note that the device provides soft-start when system rail is ramped up. When the system rail is below 2.2 V, the input current is limited to is to 200 mA. After the system rises above 2.2 V, the device limits input current to the value set by ILIM pin.

    Please visit https://e2e.ti.com/support/power-management/f/196/t/890626 for BQ25606: Schematic Review and PCB Layout Design Tips. Additional Information is available http://www.ti.com/lit/an/slva924/slva924.pdf Designing A Standalone Single Cell 3-A Charger with the bq25606.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Intellectual 465 points

    Hi,

    Thanks for your prompt reply.

    The behavior you described is what I expected.

    But I still have difficulty understanding what was mentioned in section 10: Power Supply Recommendations:

    In order to provide an output voltage on SYS, the BQ25606 device requires a power supply between 3.9 V and 13.5 V input with at least 100-mA current rating connected to VBUS and a single-cell Li-Ion battery with voltage > VBATUVLO connected to BAT. 

    Or it is just as a recommendation and I got confused by the strong wording like "requires",  "and".

  • 0 in reply to Jay Yeh
    TI__Guru 57651 points

    Hi,

    The power supply recommendations are for charger evaluation purpose only.

    Thanks,

    Ning.