BQ25120A: BUVLO not working

Hi Alp,

Can you please share a bit more with regards to the device status:

- Is there an input voltage present? If so can you measure VIN, VPMID, VSYS and VLDO when battery voltage is above and below BUVLO

- Can you please share the schematic for this application? Please include any connections directly to the battery.

- Can you please share the device register values when Battery is below BUVLO?

Best Regards,

Juan Ospina

Hi Juan,

Voltage values as follows;

We were unable to mesure buvlo below buvlo. But the power consumtion below buvlo is still too high for some reason. Around 20-25 uA.

Best,

Alp Demirel

Hi Alp,

It looks like the voltage rails do fall after entering BUVLO, is that correct? Your concern is just regarding battery consumption?

Best Regards,

Juan Ospina

Hi Juan,

Yes they do fall but as the datasheet the battery fet should disconnected and power consumption should be below 50 nA. But in our mesurements they are much more higher. Around 20-25uA.

Best,

Alp Demirel

Hi Alp,

50 nA is not necessarily the quiescent current below BUVLO, rather that is the quiescent current for shipmode. 

It is recommended that as the device discharges, shipmode is entered to minimize quiescent current consumption.

I can verify typical current consumption below buvlo in lab.

best regards,

Juan Ospina

Hi Juan,

Thank you, that would be very usefull. Knowing the normal BUVLO current consumption would be great.

Best,

Alp Demirel

Hi Alp,

I'll be able to get back to you with the readings by tomorrow.

Best Regards,

Juan Ospina

Hi Alp,

The typical current consumption of the BAT pin below BUVLO that I'm seeing is around 1.2 uA. Is there any other circuitry connected to your BQ during this testings?

Best Regards,

Juan Ospina

Hi Juan,

We have other components but they are only connected to 1.8V and 3.3V output of the BQ. SYS is set to 1.8v and LS/LSO is set to 3.3V.

Best,

Alp Demirel

Hi Alp,

Sorry, to clarify I meant any components connected to the battery pin or the BQ_MR pin.

Best Regards,

Juan Ospina

Hi Juan,

Bat Negative is connected tot he ground net and batt Positive is directly connected to the bq with the reccommended cap as shown in the schematic. BQ_MR pin is connected directly to the mcu and programmed as open drain output.

Best,

Alp Demirel

Hi Alp,

Can you confirm quiescent current into the MCU pin while it is in this state? The MR pin has an internal pull-up to BAT which is a possible path through which additional quiescent current can be pulled.

Best Regards,

Juan Ospina