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bq27500 and bq27541

A K
Intellectual 905 points
Other Parts Discussed in Thread: BQ27500, BQ27541, BQ27541-G1, BQ27510

How is the calibration profile affected if two single cells are connected in parallel to the battery pack instead of a single cell?

BQ27500

Calibration:
- Documentation states that calibration should be done on the host system. How much accuracy error is introduced if calibration is done on the EVM instead?

Production programming:
- The main board does not have access to the I2C lines so will have to use FlashStream.exe application to generate dffs file. Where can I find it?
- Do I need to download firmware+dataflash constants (bqfs file) or just the dataflash constants (dffs file)?

BQ27541

- Can this IC be used for system side implementation?
- Would like to have interrupts for battery insertion/low/good like BQ27500, but this IC does not have those. Read about HDQ interrupt functionality but is it available simultaneously with I2C? If not,  looks like Flags() command can give state of charge warnings but are there any status registers that provide battery inserted?

 

 

  • 0
    TI__Genius 14985 points

    Calibration:

    The calibration of Current is the most important one and will take into account any offset due to your layout and especially the actual value of your sense resistor.  Your sense resistor value will probably be slightly different from the one on the EVM, so if you use calibration values from the EVM in your golden file then absolute current measurements may be off slightly in your system.  This can actually be overcome after some operation time, since current measurement error will end up scaling your Qmax and Ra values in dataflash as the gauge learns after a cycle or two.  However, for maximum initial accuracy you really want to calibrate the current measurement of the gauge in your real system.  Voltage and temperature calibration are not so important.  Just leave the offsets at zero if you can't calibrate in your system.

    Production programming:

    To get Flashstream, see the files in my profile. 

    bq27541:

    - Some customers have indeed used it for system-side implementation although it was designed to be used inside a battery pack.  It only learns and updates one battery profile so it's best used with an embedded/non-removable battery.  The latest version (bq27541-G1) does indeed have some nifty interrupt functions (battery levels and temperature thresholds, for example) using either the HDQ pin or the SE pin.  Unfortunately it does not detect battery insertion since it is expecting to always be connected to a cell.  Only the system-side gauges (like bq27510 or bq27520) have the BAT_DET bit and battery detection feature.

  • 0 in reply to dMax
    Intellectual 905 points

    Thanks for the clarification and the Flashstream application!