BQ25890: BQ25890: Power setting time

user5848839

Part Number: BQ25890

I found the BQ25890 in using, from the power supply input +5V to SYS output 3.7v, the setting time is 3s.

I would like to ask whether this time is normal, whether there is a way to shorten?

As shown in below picture, the power on the REGN follows the VBUS with an interval of about 300ms, which is consistent with Figure49 in the manual.But notice a small drop in REGN about 3 seconds later

As shown in below picture, VSYS increased from 3.9v to 4.2v about 3s after electrifying VBUS, indicating that the time was too long.Please help analyze this phenomenon.

over 7 years ago

0 Ning T over 7 years ago

TI__Guru 62641 points

Hi,

Please refer to the d/s for typical start-up waveforms. Please double-check your board and test setups.

Thanks,

Ning

Please click "This Resolved my issue" button if this post answer your question.

0 user5848839 over 7 years ago in reply to Ning T

Prodigy 210 points

My schematic follows the D/S reference circuit, but the power setting waveform is not correct. Please help to check my schematic, and help to find and solve the problem of long charging delay time. Thanks!

0 Ning T over 7 years ago in reply to user5848839

TI__Guru 62641 points

Hi,

The charger output start-up time is heavily dependent on the D+/D- input source. What are REG0B and REG0C values right after powering up?

Thanks,

Ning.
Please click "This Resolved my issue" button if this post answer your question.

0 user5848839 over 7 years ago in reply to Ning T

Prodigy 210 points

In my design , The actual circuit D+=D-. The parameters of the measured register are as below: (1) REG0B=67, REG0C=85 (battery not connected) (2) REG0B=76, REG0C=00 (connect battery)

Can the above parameters show that the power on delay is normal ?

0 Ning T over 7 years ago in reply to user5848839

TI__Guru 62641 points

Hi,

Yes, it is normal for D+/D- short together.

Thanks,

Ning.

Power management

Power management forum

BQ25890: BQ25890: Power setting time