BQ25895: Device charging intermittently and only sometimes when plugged im

Horace Wang

Part Number: BQ25895

I have a device using the BQ25895 and I'm having problems having it charge consistently. Most of the time, when I plug the device in for the first time, the charger status indicator goes into fault. . I've tested this with multiple chargers. Here are the registers when the device starts charging properly

7F 05 30 0A 20 13 5E 8D 03 44 93 02 00 14 49 49 3A 19 0A 3F 39
7F 05 30 1A 20 13 5E 8D 03 44 93 62 00 14 49 49 3A 99 0A 3F 39
7F 05 30 1A 20 13 5E 8D 03 44 93 76 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 76 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 76 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 76 00 14 49 49 3A 99 0A 30 39

But most of the time, I get this

48 05 30 0A 20 13 5E 8D 03 44 93 02 00 14 49 49 3A 19 0A 08 39
7F 05 30 1A 20 13 5E 8D 03 44 93 62 00 14 49 49 3A 99 0A 3F 39
7F 05 30 1A 20 13 5E 8D 03 44 93 66 00 14 49 49 3A 99 0A 08 39
7F 05 30 1A 20 13 5E 8D 03 44 93 66 00 14 49 49 3A 99 0A 08 39
7F 05 30 1A 20 13 5E 8D 03 44 93 66 00 14 49 49 3A 99 0A 08 39
7F 05 30 1A 20 13 5E 8D 03 44 93 66 00 14 49 49 3A 99 0A 08 39

I've also had the device stop charging abruptly and go into fault with no apparent change in status registers

7F 05 30 1A 20 13 5E 8D 03 44 93 76 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 76 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 76 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 76 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 66 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 66 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 66 00 14 49 49 3A 99 0A 30 39
7F 05 30 1A 20 13 5E 8D 03 44 93 66 00 14 49 49 3A 99 0A 30 39

Is there anything in my hardware that could be causing issues?

over 5 years ago

0 Ning T over 5 years ago

TI__Guru 57611 points

Hi,

The VBUS status does not look stable and sometimes no Input/No Power Good (REG0B=02). Please double-check VBUS pin voltage.

Please visit https://e2e.ti.com/support/power-management/f/196/t/874557 for BQ2589X: Schematic Review and PCB Layout Design Tips and https://e2e.ti.com/support/power-management/f/196/t/875386 for BQ2589x/BQ25898x FAQs.

Please watch the video below for charger operations and valuable tips.

Battery charger system overview (training.ti.com/battery-charger-system-overview

Battery Charger Common Issues: Why my Battery is Not Charging (training.ti.com/battery-charger-common-issues-why-my-battery-not-charging

If you still have questions after going though the information, please feel free to let us know.

Thanks,

Ning.

0 Horace Wang over 5 years ago in reply to Ning T

Prodigy 40 points

Hello,

The register line with REG0B = 02 is immediately before insertion of the USB plug. I've included a scope capture of the VBUS pin on pin on USB insertion.

I'm reviewing the sample drivers and reference schematics to see if there is anything of note.

0 Ning T over 5 years ago in reply to Horace Wang

TI__Guru 57611 points

Hi,

What are your test conditions such as VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS when it charges normally and when it does not charge respectively?

Thanks,

Ning.

0 Horace Wang over 5 years ago in reply to Ning T

Prodigy 40 points

I need to set up measurements for current, but I did notice that when It was charging off my computer, the VBUS was 4900mV while it returned 5100 mV when it was not charging.

48 05 30 3A 20 13 5E 8D 03 44 93 36 00 14 4C 4C 4A 97 0A 48 39

48 05 30 3A 20 13 5E 8D 03 44 93 26 00 14 4B 4D 3A 99 00 08 39

I noticed that in my schematic that the boost capacitor was too large. However, replacing it with a 0.047uF did not solve the intermittent charging issue.

0 Horace Wang over 5 years ago in reply to Horace Wang

Prodigy 40 points

The VBUS voltage when charging is 4.98V and the current is 0.46A. I've attached a scope waveform of a successful charge. I have an older revision board that seems to charge every time I plug it in where the VBUS voltage doesn't hit 5100 mV before entering the charge state.

0 Ning T over 5 years ago in reply to Horace Wang

TI__Guru 57611 points

Hi,

When not charging, REG13=48 (not 08) indicates IINDPM status. And VBUS voltage drops to 4.9V from 5.1V. Please refer to 8.2.6.2 Dynamic Power Management on the d/s and https://e2e.ti.com/support/power-management/f/196/t/875386 BQ2589x FAQ#3 for the details.

Thanks,

Ning.

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BQ25895: Device charging intermittently and only sometimes when plugged im