BQ25672: Battery consumption

Hi Jeff

There is a VBUS 12V, and the battery is in range from 7.5 to 8.2V. I have seen that this current draw has a constant value with no spike between the trickle charge periods.
When the external power is disconnected, the BQ25672 correctly disables the ship FET, and the current drops to 17uA.

For example, below is a plot of voltage and current drawn from the battery with VBUS 12V.

Battery connected to BQ25672 through an FET, which protects the battery against charge (internal charge termination function), and the voltage on bat pins comes trough the body diode of FET.

Circuit is same as in this question, with default configurations. e2e.ti.com/.../bq25672-bq25672-reregulation-vsys
There is passed condition that VBUS>VBAT, but I still see current draw from the battery, and configuration like disabling ADC or something else does not affect this.I would like to increase as much as possible the recharging period for the battery, so this question is repeated.

Best Regards,
Serhii

Hi Serhii,

Do you by chance have REG0x14[5] = 1 to turn on IBAT ADC during HiZ?  I recently learned that this can cause high IBATq even if ADC is not enabled.

Regards,

Jeff

Hi Jeff,

If you mean these steps: set bit EN_HIZ -> set bit EN_IBAT pin -> clear EN_HIZ

That did not affect the battery consumption in mode with a VBUS adapter.

The only thing that increases consumption from the battery is disabling PFM in charge mode, it increases the consumption to 400uA.

Here are my test settings: and the consumption with REG0x14[5] = 1:

Thanks,

Serhii

Hi Serhii,

Sorry for the confusion.  I meant to set EN_IBAT_pin = 0.  If that did not help, then the only way to reduce current is to set EN_HIZ=1, which turns off the converter and let's the battery provide the SYS voltage.

Regards,

Jeff

Hi Jeff
Unfortunately, that is not my case.
I have an external power supply, and I don't worry about the current that I draw from the adapter power supply. I am worried about the next case: The external 12V adapter is connected. The battery is also connected. BQ25672 provides the current path from the adapter to VSYS, which is expected. However, the BQ25672 draws some current from the battery, which provides faster battery discharge in simple mode connected to the BQ25672, which is unexpected for me.
That current is about 380uA. 
I don`t see that it is specified in the datasheet. Could you provide whether BQ25672 works as expected?

Regards,
Serhii

Hi Serhii,

Unfortunately, that battery discharge current is not unexpected while input voltage is attached.  After termination, if you want to prevent battery discharge current and more frequent recharges, you will need to add a PFET between BAT and battery pack.  The PFET can be turn off to disconnect the battery from the charger. 

Regards,

Jeff 

Thank you Jeff for your answer.

I do not clearly understand how to drive that PFET to keep full functions of the BQ25672, like Ship/shutdown mode, DPM, and other functions on the BQ25672 side. Is there an example for the circuit?