BQ27621-G1: Current Consumption of the IC

Ankit Nikumbh

Part Number: BQ27621-G1

Hello,

We are using BQ27621 Fuel gauge IC for our prototype design which is battery operated. We have put the jumper to measure the current consumption of the IC. We found that as per datasheet, it should consume 27uA current in normal/active mode but using 6 1/2 DMM we measured that current around 56uA. So we don't know why it is consuming this much of current.

Will you help me to understand how and where this much current is going?

Here I have attached the schematic snap of the IC and the measurement point is jumper J1.

over 5 years ago

0 Onyx Ahiakwo over 5 years ago

TI__Guru* 76230 points

Hi Ankit,
when you disconnect the i2c cable, do you see the current drop? I would recommend using a larger pull up value for the clock and data lines, some thing like 5.1k
thanks
Onyx

0 Ankit Nikumbh over 5 years ago in reply to Onyx Ahiakwo

Prodigy 60 points

Hi Onyx,

Thanks for your response.

Yes, I have tried to disconnect the i2c but still the same current we are getting. When we connect the battery once after disconnection, then the same amount of current it consumes. I don't know in which state Fuel gauge is working.

By default in normal mode(27uA) fuel gauge is working when the battery is detected/connected right?

0 Onyx Ahiakwo over 5 years ago in reply to Ankit Nikumbh

TI__Guru* 76230 points

Hi Anikit,
How are you measuring this current? is it the average current you are measuring or are you looking at the peak value. Do you have a scope shot of your current measurement? Can you use the 5.1k pull ups i recommended so we see if that makes a difference? Where does VCC on your schematic connect to ?
thanks
Onyx

0 Ankit Nikumbh over 5 years ago in reply to Onyx Ahiakwo

Prodigy 60 points

Hi Onyx,

I am measuring the current using 6 1/2 Digit DMM which gives instantaneous values. Here I have attached the current reading image which shows the reading across the header J1.

I have also tried with 5.1k pull-up resistors which also gives the same result, no change in current drop. Vcc is 1.8V net comes from the Buck output. and SoC is also running at 1.8V through which fuel gauge is communicating.

0 Onyx Ahiakwo over 5 years ago in reply to Ankit Nikumbh

TI__Guru* 76230 points

Hi Ankit,

The way we measure is we take the average current over a given time frame, eg 10s. We capture with a scope and take the average value. The currrent draw from the gauge isn't a constant value the whole time. It depends on what the gauge is doing at any given time.

thanks

Onyx

0 Ankit Nikumbh over 5 years ago in reply to Onyx Ahiakwo

Prodigy 60 points

Hi Onyx,

Sorry for the delay.

I have measured the average current using the Nordic's Power Profiler Kit for 2 mins. See the attached image for your reference.

Let me know about this issue. Help me to get lower consumption of the chip.

0 Onyx Ahiakwo over 5 years ago in reply to Ankit Nikumbh

TI__Guru* 76230 points

Hi Ankit,
Do you have an EVM to test. This will help narrow down if something on your board is causing the increased current draw.
thanks
Onyx

0 Ankit Nikumbh over 5 years ago in reply to Onyx Ahiakwo

Prodigy 60 points

Hi Onyx,

No, I don't have EVM. But while measuring, we have seen that the Gas Gauge can go in shutdown mode by taking 0.6uA(as per datasheet). But in a normal mode of operation the consumption is very huge.

Thanks
Ankit

0 Onyx Ahiakwo over 5 years ago in reply to Ankit Nikumbh

TI__Guru* 76230 points

Hi Ankit,

I strongly feel you are missing something. This might be circuit related. Or perhaps just that IC related. Pls acquire an EVM so as to be able to have a point of reference.

thanks

Onyx

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BQ27621-G1: Current Consumption of the IC