BQ25756: Please review the schematic

Chase Jeong

Mastermind 7905 points

Part Number: BQ25756

Tool/software:

Dear TI experts,

My customer drew their first schematic with BQ25756. Could you review it?

- Cell chemistry : LiFePO4

- Cell structure : 4S1P / 4S2P / 4S3P / 4S4P (Parellel structure varies.)

- Input voltage : 12V ~ 40V

- Standalone structure (not I2C controlled)

BQ25756-2.pdf

And one more question,

If the charger stops charging due to applying low to ACUV, hoiw much is the current consumption at this time?

Best regards,

Chase

over 1 year ago

0 Ethan Galloway over 1 year ago

TI__Mastermind 32195 points

Hello Chase,

Thanks for being patient with this. I'll get back to you later this week on this.

Best Regards,
Ethan Galloway

0 Chase Jeong over 1 year ago in reply to Ethan Galloway

Mastermind 7905 points

Dear Ethan,

Thank you for your support.

I understand. Please let me know if there are updates about the issue above.

Best regards,

Chase

0 Ethan Galloway over 1 year ago in reply to Chase Jeong

TI__Mastermind 32195 points

Hello Chase,

I will respond back tomorrow about the schematic.

For the charger stopping during ACUV, it should be around 0.75mA.

Best Regards,
Ethan Galloway

+1 Ethan Galloway over 1 year ago in reply to Ethan Galloway

TI__Mastermind 32195 points

Hello Chase,

Thanks for working with us on this.

Here are suggestions for the schematic:

Make sure to have at least 80µF of capacitance on VBAT and VAC spread across the sense resistors. Please see this FAQ for more information.
Make sure that the switch node capacitance doesn't exceed C_SW(nF) < 160/VIN. For reference, you can find this information in page 65 of the datasheet
The inductance might be too small. The minimum inductance for the charger is 2.2 µH and maximum is 15µH.
Keep in mind that the inductor DCR needs to be between 1.75mΩ and 60mΩ.
When the ICHG or ILIM_HIZ resistors are greater than 5kΩ, we recommend installing an RC filter in parallel with them. The ICHG resistor will need the RC filter in the schematic.

Once again, thanks for being patient with this. Let me know if you have any questions about this.

Best Regards,
Ethan Galloway

0 Chase Jeong over 1 year ago in reply to Ethan Galloway

Mastermind 7905 points

Dear Ethan,

Thank you for your support.

I shared your suggestion to my customer. I will reply if my customer have more question.

Best regards,

Chase

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BQ25756: Please review the schematic