BQ25886: When the battery is not connected to the charger

R.Fukunaga

Expert 2505 points

Part Number: BQ25886

Tool/software:

Hi all,

I would like to ask about VSYS output.

When the battery is not connected to the charger

The waveform when a load of 1A is applied is shown below.

CE pin is low.

The voltage drops to VSYS=0V at 1A load. Is this normal?

Is there a solution?

If a load is applied when VSYS falls from 8.4V to 6.4V, the voltage drops to 0V.

If a large capacitor is connected to the VBAT, is it possible to make IC recognize that the battery is always connected?

Best Regards,

Ryusuke

over 1 year ago

+1 Ning T over 1 year ago

TI__Guru 57741 points

Hi,

The charger does not have battery detection feature.

Please disable charge and try again.

Thanks,

Ning.

0 R.Fukunaga over 1 year ago in reply to Ning T

Expert 2505 points

Hi Ning,

Thank you for your reply. It was solved by changing CE pin to H.

I have an additional question.

Is D7 (diode between VBAT and VSYS) described in the EVM circuit diagram necessary?

BQ25886 QFN boost-mode battery charger evaluation module

I understand that it is unnecessary because of the body diode of IC internal FET (Q4).

BQ25886 Standalone 2-Cell, 2-A Boost-Mode Battery Charger With PowerPath, USB BC1.2 Detection, and USB On-The-Go Boost (OTG) datasheet (Rev. A)

Best Regards,

Ryusuke

0 Ning T over 1 year ago in reply to R.Fukunaga

TI__Guru 57741 points

Hi Ryusuke,

It should be optional.

Thanks,

Ning

0 R.Fukunaga over 1 year ago in reply to Ning T

Expert 2505 points

Hi Ning,

Thank you for your reply.

If it is optional, is it correct to delete it?

Do you know the purpose for which D7 is placed?

Best Regards,

Ryusuke

+1 Ning T over 1 year ago in reply to R.Fukunaga

TI__Guru 57741 points

Hi Ryusuke,

It helps to reduce power dissipation and it is not a must-have.

Thanks,

Ning.

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BQ25886: When the battery is not connected to the charger