BQ25887: BQ25887EVM schematic questions

Benjamin Linne

Part Number: BQ25887

Tool/software:

Hi,

I'm looking at the BQ25887EVM and I had a few questions.

1. Are the input and output shunt resistors R1 and R6 necessary for operation? I didn't see the voltage drop across them connected back to the BQ25887

2. What is the purpose of D7 which connects Bat to SNS_SYS

3. What happens if a load is placed on the battery while it's under charge?

- When the load is less than the charge current will it continue to charge and is it possible to restart charging after completion to keep battery topped off?

- When the load is more than the charge current and VBAT > VBATLOWV will the charge stay in fast charge CC?

4. Can you verify my simplified schematic attached looks good?

2211.output.pdf

2 months ago

0 Ning T 2 months ago

TI__Guru 51901 points

Hi,

1. Optional

2. To reduce power dissipation.

3. In this case, the charger can't tell the current going to the battery and the current going to the load respectively. The charger will control the total current going out of the BAT pin per the target charge current settings.

4. The schematic seems ok without obvious error. Please double-check with 9.2 Typical Application and the EVM schematic.

Thanks,

Ning.

0 Benjamin Linne 2 months ago in reply to Ning T

Prodigy 20 points

Hi,

I had another question.

1. Is it okay to short ILIM to GND?

2. If PSEL is set high to REGN and ILIM is shorted to GND, is the input current still limited to 500mA?

Thanks,

Ben

0 Ning T 2 months ago in reply to Benjamin Linne

TI__Guru 51901 points

Hi Ben,

1 Yes

2 It should be.

Please visit https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1051774/faq-bq25883-faq-bq2588x-schematic-review-and-layout-tips-for-bq25882-bq25883-bq25886-and-bq25887 for the BQ2588x schematic checklist.

Thanks,

Ning

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BQ25887: BQ25887EVM schematic questions