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BQ27200 EEPROM programming

Ran Aloni
Expert 2386 points
Other Parts Discussed in Thread: BQ27200

Dear all,

I'm using the BQ27200 in a very small PCB.

I place a test point on PGM PIN in order to access EEPROM.

in the datasheet it is not well elaborated.

I want to create the 21V pulse from an external power supply, meaning, applying a pulse of 21V to the PGM and use BQ easy for 27200 software to apply EEPROM values.

  1. is it possible?
  2. what is the longest pulse I can apply? does it have to be 50mS, or can I apply it for a sec before programming?
  3. how much time after applying the pulse can I write to EEPROM? datasheet doesn't clearly say?

I'm  obviously trying to use standard power supply to write to EPROM without extra circuitry or MCU firmware writing.

thanks for any assistance,

Ran Aloni

  • 0
    Prodigy 90 points

    Hi Ran!

    I have a similar problems with this IC. It hasn't got some info for configurate EEPROM and registers.

    But i could change values in EEPROM... You must to keep a 21V pulse more time (a few seconds)  and then if u can't read all the register with "I2Cget" so u will be change the EEPROM values. 

    After that, reset  the device...and read the EEPROM...

    My values were changed with these steps. i  hope u will have the same result! 

    If you have the clue for change VDQ flag, please help me! for me it's impossible change to 1 this flag :(

  • 0 in reply to Javo Barragan
    Expert 2386 points

    thanks a lot!

    I ended up using the BQ27200 EVM to create a small JIG for programing.

    about VDQ, from what I've read, it is a read only BIT, that is changing to 1 only when a valid discharge has ended.
    so when the cell passes the EDV (end discharge voltage) qualifier.

    does the LMD value only changes when VDQ is 1? is this the problem?

    even if you write to EEPROM?

    if so, it is very problematic to release batteries without a discharge.


    regards,

  • 0 in reply to Ran Aloni
    Prodigy 90 points

    your welcome Ran!

    Yes VDQ is a read bit...
    My problem is that i haven't got BQ.. EVM. So I want to modify the parameters with I2C instructions, like i2cget, i2cset, etc.
    I could change the EEPROM values but VDQ pin never turn to 1, even my battery down the voltage less than EDV.
    I have a Li-ion battery with 3.7V and 3000mAh capacity. in your opinion, how to configure the EEPROM values?
    Thanks and sorry for my english, I'm Latino :P
  • 0 in reply to Javo Barragan
    Expert 2386 points

    Dear Javo,

    take a look at page 11 of datasheet.

    there are 7 options where VDQ is not set even if EDV1 is met.
    EDV1 is a voltage you set that is a bit higher than EDV final (usualy 3V).

    I would set EDV1 to be 3.35V (not much left afterwards) and EDV 3.05V.

    ISLC to be 40mA, and the rest is not so crucial.

    I would suggest to set EDV1 a bit higher then EDV, and use a low current (but not lower then 2x standby current which you defined - ISLC), to give the system enough time to identify a complete end of discharge).

    I would recommend you to have the EV2300 (or similar) and use the TI software, it will make your life easier to understand the chip.


    BTW- your English is perfect :-)

    best regards,

  • 0 in reply to Ran Aloni
    Expert 2386 points

    Dear Javo,

    more info:

    you can force the true ILMD value (your case ~3000mAh) , with EEPROM overwrite, and that will make it easier for the bq to identify end of discharge.

    also, if you set the taper current and QV (qualified voltage - charge), and perform a charge that meets this parameters in the end- you will get VDQ = 1.

    regards,