BQ25887: Can't enable ADC without VBUS

Stone Zeng

Part Number: BQ25887
Other Parts Discussed in Thread: BQSTUDIO,

Tool/software:

Hi Team,

i am testing BQ25887EVM with BQSTUDIO. With 5V input, i set ADC at continuous mode with15b sample rate, then i enable ADC, the bqstudio can read both VBUS and VBAT correctly. if i remove VBUS and connect a 7v battery to EVM battery connector. the BQSTUDIO can communicate with the EVM, but i can't enable ADC( set 0x15 bit7 to 1, while read value is 0), could you please help check this and advise is there anything else i can do?

Regards,

Stone

25 days ago

0 Ning T 24 days ago

TI__Guru 57621 points

Hi Stone,

What are your test conditions such as VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS? Could you please provide all register readings of the charger including ADC?

Thanks,

Ning

0 Stone Zeng 24 days ago in reply to Ning T

TI__Prodigy 700 points

Hi Ning,

The test condition is connecting a 7v battery to EVM battery connector, there is no VBUS, no system load, no battery load.

With VBUS(5V), I can enable ADC(set 0x15 bit7 to 1) correctly with BQSTUDIO. Without VBUS, I can't enable ADC with BQSTUDIO.

+1 Ning T 23 days ago in reply to Stone Zeng

TI__Guru 57621 points

Hi,

How did you connect the battery terminals? Please refer to Figure 69. BQ25887 (Cell Balancing and I 2C) Typical Application Diagram on the d/s.

Thanks,

Ning

0 Stone Zeng 10 days ago in reply to Ning T

TI__Prodigy 700 points

Thanks Ning, connect low side cell battery to MID pin, the ADC works well now.

0 Ning T 9 days ago in reply to Stone Zeng

TI__Guru 57621 points

Hi Hi Stone,

Great! The thread is resolved and closed.

Thanks,

Ning

Power management

Power management forum

BQ25887: Can't enable ADC without VBUS