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bq35100

Danylo Vodopianov
Prodigy 40 points
Other Parts Discussed in Thread: BQ35100

Hello, I worked with driver BQ35100 in EOS mode.

When I want to read voltage current and internal temperature, I use next flow

1) GE enable

2) GE start

3) wait 100ms

4) GE stop

5) read voltage current and internal temperature

6) GE disable

I have 2 questions.

First, between step 1 and 6 it can takes about 15-20 secods, is it nornal time frame ?

Second, when I get current, my device consumes about 50mA , but driver does not always return right value(about 50 mA), time to time it return from 5 to 20 mA.

Thank you.

  • 0
    TI__Genius 10370 points

    Danylo,

    If you only want Voltage. Current. and temperature you should not be using EOS mode. When you issue the gauge start command the gauge alternates V,I measurements every 8mS which is not a long conversion time. There is a lot of error introduced there.  The gauge corrects this error by averaging a lot of samples. When the gauge start command is issued the gauge is expecting a burst load to see a voltage delta and allow it to calculate an impedance. If you are not giving this burst the EOS algorithm will not work and eventually breakdown.

    The best mode to use for your purpose will be accumulation mode. 

    Thanks,

    Eric Vos

  • 0 in reply to Vos
    Prodigy 40 points

    Eric, thank you for your answear.

    But I don't understand, why I can not use EOS mode? The main reason, why I decided to use EOS mode, it is because I have Li-SOCl2 battery, according TRM End-of-service (EOS algorithm for Li-SOCl2 ) use for this type of battery.  Also according TRM rev.C, Figure 6-2. Operational Flow, driver updates Current only if GMSEL= 10, in another modes driver updates Coulomb Counter.

    In general I need EOS mode for my project and time to time I want to get Voltage, Current and Temperature. Which is best solution for me in my situation? Is it possible to change mode on accumulation when I want to get Voltage, Current and Temperature and then change back to the EOS ?

    I tried accumulation mode and device showes me the same values like in EOS mode, Temperature and Voltage is ok, but Current is about 36 mA, but according avometer it should be about 50 mA. Is it average Current, not actual?

    Also, can you answer me, what is it EOS Gauge Load Current ?

    It also takes about 20 seconds between I enable gauge and read parameter in accumulation mode.

    Thank you.

  • 0 in reply to Danylo Vodopianov
    TI__Genius 10370 points

    Danylo,

    If you want to use the EOS mode you can leave the device in EOS mode to get voltage current and temperature. What is critical is when you are only enabling the gauge for V/I/T data do not issue the gauge stop command. The gauge stop command is what triggers the gauge to do the EOS mode calculations. I would allow the gauge to take lots of samples to average prior to reading the current register after the gauge start command is issued. 

    Current is a 1 second average, but in EOS mode it is slightly different because the sampling period is different than traditional. In EOS mode you current will not be as accurate as accumulation mode. 

  • 0 in reply to Vos
    Prodigy 40 points

    I see, thank you for your help.

    Now I run Accumulation mode for my device and I have next flow.

    1) Enable Gauge

    2) Wait for INITCOMP = 1

    3) Get Voltage and Temperature

    4) Disable Gauge

    This works for me and I have right results.

    But when I want to get Current with this flow, which I described above, I get wrong Current values. I get 0 (zero) mA.

    If I run this in another way:

    1) Enable Gauge

    2) Wait for INITCOMP = 1

    3) Start Gauge

    4) Wait for Gauge start

    5) Wait 2 seconds

    6) Get Current

    7) Stop Gauge

    8) Wait for G_DONE

    9) Disable Gauge

    It works for me, but it returns bigger value. My device consump 5 mA, but device return about 20 mA.

    Can you help me with this issue ?

  • 0 in reply to Danylo Vodopianov
    TI__Genius 10370 points

    Danylo,

    In accumulation mode [Gauge Start] command is still needed in order to have the gauge start taking measurements. Issuing the [Gauge Stop] command in this mode commits whatever charge has been accumulated since [Gauge Start] into flash. Powering the device down without Gauge Stop will just not save the charge seen. 

    Thanks,
    Eric Vos