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Original question:

BQ27426: bq27426 consumption pulses

BQ27426: Consumption in Sleep mode BQ27426

Avraham Bergel
Prodigy 40 points
Part Number: BQ27426

Tool/software:

Hi,

  1. We use the bq27426 in your EVB and the battery management studio . 

Only Battery is connected to Evb and I2c cable and there is no load connected,

The FG is in sleep mode according to the battery management studio (Flag status) .You can see attached Pic.1.

We measure the input current of your EVB with a current logger connected in series to the battery and I disconnect the cable of the I2c from EVB. 

In this condition we see that the Fuel Gauge generates a current consumption pulse every 48 sec (width of 1sec), and several other pulses . The pulses are of around 240uA. You can see the attached  Pic. 2.

According with the TR page 10 its mentioned  :

During SLEEP mode, the fuel gauge remains in a very-low-power idle state and automatically wakes up briefly every 20 seconds to take data measurements.

 

So I understand that every 20 second the FG wakes up to measure voltage, average current and temperature, my question is this happens in one operation (one pulse current) or in 3 steps (3 pulses).

In addition when we send to the Fuel Gauge the ShutDown command, the pulse disappears.

Can you explain the reason of these pulses that i received? 

Is this an expected behavior?

     2. According to data sheet page 5, section 6.5- Supply Current table and about note (2) how I can deactivate the wake comparator to be able to obtain 9uA consumption. You can see attached Pic 3.

Thanks,

Avraham.

  • 0
    TI__Genius 16476 points

    Hello, 

    These are the expected behavior of the gauge. When you are measuring the iq of the gauge, it is important to take the average over a 30 second period at least. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 40 points

    Hi,

    Can you tell me how to obtain the wake comparator disable which was cited in note (2) to receive 9uA of current from sleep mode ,please see Pic3

  • 0 in reply to Avraham Bergel
    TI__Genius 16476 points

    Hello, 

    In order to achieve the 9 uA typical sleep current, the gauge must be in sleep mode. The Sleep mode can be entered if OpConfig[SLEEP] = 1, and the AverageCurrent() is less than the programmable Sleep Current level (10 mA by default). Once the gauge has entered Sleep mode, you can then measure the gauge iq, and you should report an average iq (sampled at least over a 30 second interval) of about 9 uA (typical). 

    Regards, 

    Jonny.