BQ25303J: BQ25303J fuel gauge connection

Dimiter Kendri

Part Number: BQ25303J

Hello,
we are using the BQ25303J in conjunction with an STC3100 fuel gauge in a client application. The issue is the fuel gauge is always saturated when a USB plug is connected to the device reporting always 100%.

since the SW node must be connected to the BAT pin. The STC3100 uses a low side sense resistor. How can we modify the BQ25303 schematic to handle the battery input current when the USB is plugged in. Resistor R38 (33 mohm) is good for 2A.

3113.Sheet1.pdf

over 1 year ago

0 Ning T over 1 year ago

TI__Guru 57811 points

Hi,

We will check and get back to you this week.

Thanks,

Ning.

0 Dimiter Kendri over 1 year ago

Prodigy 10 points

Hi,

Any updates on this?

the BQ25303 was already working but I'm trying to confirm how to interface the existing fuel gauge or if it's compatible with switching chargers. The BQ25303 is powered either by a LIPO or a USB3 cable or both at the same time.

0 Ning T over 1 year ago in reply to Dimiter Kendri

TI__Guru 57811 points

Hello,

This sounds more like a question for the gauge. Please check with the gauge vender.

Thanks,

Ning.

0 Dimiter Kendri over 1 year ago in reply to Ning T

Prodigy 10 points

The question was if the switching charger is compatible with the fuel gauge or if there are any other LIPO gauges that can be used with it. There are no reference designs for it.

+1 Ning T over 1 year ago in reply to Dimiter Kendri

TI__Guru 57811 points

Hello,

The BQ25303J d/s shows the typical applications for the charger. To avoid the charger and the gauge interfering with each other, a potential workout could be to take out the voltage across the sense resistor and isolate the signal by op amp as an example then feed into gauge.

If help is needed for TI gauge selection, please submit a separate thread and a TI gauge expert will support.

Thanks a lot,

Ning.

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BQ25303J: BQ25303J fuel gauge connection