BQ25790: In trouble with the charging mode

Sébastien THORAVAL

Part Number: BQ25790

Dear M. or Miss,

I'm currently using a BQ25790YBGR to manage a battery in a design.

We have no problems when the battery is used but impossible to charge it. Is it possible to have a review of the design which could explain this?

We have an error somewhere (the PIN STAT goes from 0 to 1 at 1HZ). I supposed it comes from the TS or the ILIM because I'm not sure of the design on these pins.

Thank you for your help,

Best regards,

S.T

over 3 years ago

0 Jeff F over 3 years ago

TI__Guru*** 148825 points

Hi S.T.

Can you provide your schematic and your registers settings?

Regards,

Jeff

0 Sébastien THORAVAL over 3 years ago in reply to Jeff F

Prodigy 40 points

Sure :

0 Sébastien THORAVAL over 3 years ago in reply to Sébastien THORAVAL

Prodigy 40 points

We have the default register settings. I don't have access to the register for now. Only the physical signals

0 Jeff F over 3 years ago in reply to Sébastien THORAVAL

TI__Guru*** 148825 points

Hi S.T.,

The schematic looks okay. The flashing STAT indicates a fault. The status and fault registers will tell you which fault. Is your battery thermistor a 10kohm? Is the issue only when you remove the battery or can you not charge even when the battery is connected?

Regards,

Jeff

0 Sébastien THORAVAL over 3 years ago in reply to Jeff F

Prodigy 40 points

Hi Jeff,

For instance I have a battery without thermistor then I saw that I'have no thermal control. (because I have a constant 4.26V on TS, it should'nt be a reason for uncharge).

I have 6.60V (voltage of my battery which reduce when I don't supply my board with 12V) but no current on the BAT line. (0.006mA measured on the battery + when it should charge). When I have no battery, I have 7.24V output which seems strange too because if I understand the datasheet, the selected mode is a 8V output.

I have no material to check the current without battery.

Regards,

Sébastien

0 Jeff F over 3 years ago in reply to Sébastien THORAVAL

TI__Guru*** 148825 points

Hi Sébastien,

For normal charge with a battery attached, V(TS) as a % of V(REGN) needs to be between

and

assuming default register settings. V(TS) =4.26V disables charge.

If a battery is not attached and charge is enabled, see the FAQ at the link below:

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1023437/faq-bq25792-why-does-the-sys-output-of-the-evaluation-module-evm-collapse-when-no-battery-or-battery-simulator-is-attached-to-the-bat-pins

If charging is disabled via the /CE pin or CE bit or TS fault and battery is below the MINSYS voltage (default MINSYS=7.2V typical for 2S battery), then V(SYS) regulates to MINSYS.

Regards,

Jeff

0 Sébastien THORAVAL over 3 years ago in reply to Jeff F

Prodigy 40 points

Thank you a lot it solves my problem !

Regards,

S.T

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BQ25790: In trouble with the charging mode