BQ25895: How to use VBUS to power external devices

Selamu Mekonnen

Part Number: BQ25895
Other Parts Discussed in Thread: PMP4496, BQ25890H

Tool/software:

Hello,

I currently designing a product using a BQ25895. The system has a battery that can be charged from VBUS, an input from USB Type C connector and also supply power to the system. I am now wondering that how we can use VBUS to power external devices, specifically USB flash drive and also how we can connect the differential pairs to the host MCU.I am using the reference design PMP4496 as a reference.

Thanks!

2 months ago

0 Ning T 2 months ago

TI__Guru 54571 points

Hi,

It should be ok to use VBUS to power other devices as long as it has enough power to support the BQ25895 charger needs.

Thanks,

Ning.

0 Selamu Mekonnen 2 months ago in reply to Ning T

Prodigy 20 points

Ning T said:
as long as it has enough power to support the BQ25895 charger needs

Hi Ning

Thank you for your information.

So if OTG pin is high and OTG_CONFIG register is set to 1 and no input source is detected at VBUS, which means VBUS can supply power to the attached device? Right?

0 Ning T 2 months ago in reply to Selamu Mekonnen

TI__Guru 54571 points

Hi,

For BQ25895, when Boost mode is enabled, only PMID is the OTG output. The converter will switch from Boost mode to charge mode automatically when valid VBUS plugs in at the VBUS pin.

Thanks,

Ning

0 Selamu Mekonnen 2 months ago in reply to Ning T

Prodigy 20 points

Hi Ning,

So there is no way we can use the battery power through VBUS, VBUS as an output?

Thanks,

Selamu.M

0 Selamu Mekonnen 2 months ago

Prodigy 20 points

Hi Ning,

Ont page 19 of the datasheet of BQ25895 it states that "During boost mode, the status register VBUS_STAT bits is set to 111, the VBUS output is 5V by default
(selectable via BOOSTV register bits)." which means the VBUS can be used as an output. Right? correct me if i am wrong. attached is the picture of datasheet.

0 Ning T 2 months ago in reply to Selamu Mekonnen

TI__Guru 54571 points

Hi,

For BQ25895, when Boost mode is enabled, RBFET Q1 is off and only PMID is the OTG output. If both PMID and VBUS need to be the boost output, please use BQ25890H instead (https://www.ti.com/lit/ds/symlink/bq25890h.pdf)

Thanks,

Ning.

0 Ning T 2 months ago in reply to Selamu Mekonnen

TI__Guru 54571 points

Hi,

Thanks,

Ning.

+1 Ning T 2 months ago in reply to Selamu Mekonnen

TI__Guru 54571 points

Hi,

Thanks,

Ning.

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BQ25895: How to use VBUS to power external devices