BQ76952: Measuring current consumption of BQ76952 with shunt resistor in front of BAT pin

Alec Fremier

Part Number: BQ76952
Other Parts Discussed in Thread: BQ77216

Tool/software:

We would like to monitor the current consumption of the BQ76952 (and the BQ77216 for that matter). Are there any known issues + design considerations (such as voltage drop, measurement of cell voltage stack issues) with putting a very low current sense shunt resistor in front of the BAT pin (and the VDD pin on the BQ77216) to measure the current consumption?

6 months ago

+1 Alexis_H 6 months ago

TI__Genius 17835 points

Hello Alec,

Somethings to keep in mind:

1. When cell balancing is active for BQ76952, there is additional current flow into the top cell input (VC16), for each cell that is balancing. This is further explained in Section 2.5 Voltage Measurement Accuracy During Balance from the Cell Balancing Application Note.

2. If the charge pump is enabled with CP1 connected to BAT and the pin is not used, the device will consume an additional ~200uA. This is stated in Table 16-3. Terminating Unused Pins of the datasheet.

Best Regards,
Alexis

0 Alec Fremier 6 months ago in reply to Alexis_H

Intellectual 270 points

Alexis,

Thanks for your response, those are good things to keep in mind.

As long as the shunt is small enough, there shouldn't be an issue with a voltage drop across the shunt that reduces the voltage on the BAT pin?

+1 Alexis_H 6 months ago in reply to Alec Fremier

TI__Genius 17835 points

Hello Alec,

It should be fine if it is small enough.

Best Regards,
Alexis

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BQ76952: Measuring current consumption of BQ76952 with shunt resistor in front of BAT pin