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BQ24172: GND wiring both bq34z100 and bq24172

PAN-M

Mastermind 8375 points

Part Number: BQ24172
Other Parts Discussed in Thread: BQ34Z100

Dear Team,

Would you please teach me the GND wiring when I use both bq34z100 and bq24172 on the system side.
Does the wiring correct in the following figure?

4377.bq34z100_bq24172.pdf

Regards,
PAN-M

over 5 years ago

0 Wyatt Keller over 5 years ago

TI__Guru** 105770 points

Hello,

It looks to be correct as far as the grounds. You just need to make sure the resistor is in the power path by referencing the PACK- after the gauge. You can always refer to the EVM schematic if you have questions about connections. the BAT+ and PACK- are your load and charger connections.

EVM users guide: https://www.ti.com/lit/ug/sluu904a/sluu904a.pdf?ts=1592844924444&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ34Z100

Sincerely,

Wyatt Keller

0 PAN-M over 5 years ago in reply to Wyatt Keller

Mastermind 8375 points

Thank you for answer.

As my concern point is a potential difference of 40mV if a charge current is 4A at 10m-ohm, it is a point whether there is not a problem.

Thanks and Regards,
PAN-M

0 Andy Liu (BMS) over 5 years ago in reply to PAN-M

TI__Guru 52115 points

I think you were talking about the voltage drop across the sensor resistor.

Our requirement is that the input voltage generated across the current-sense resistor should not exceed ±125 mV. A voltage drop of 40mV is fine.

Andy

0 PAN-M over 5 years ago in reply to Andy Liu (BMS)

Mastermind 8375 points

It is ±125mV including contact resistance and wiring.
What value is ±125 mV?

Thanks and Regards,
PAN-M

0 Andy Liu (BMS) over 5 years ago in reply to PAN-M

TI__Guru 52115 points

I was talking about voltage drop across the sensor resistor only.

See 6.10 Electrical Characteristics: Integrating ADC (Coulomb Counter) Characteristics of bq34z100 datasheet.

Andy

0 PAN-M over 5 years ago in reply to Andy Liu (BMS)

Mastermind 8375 points

Andy,

Thank you.