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BQ40Z50 standalone mode

jury noname
Intellectual 765 points
Other Parts Discussed in Thread: BQ40Z50, BQSTUDIO

Hi all!

I try make charger circuit based on ltc4100 (custom board, 100% Compliant (Rev. 1.1) SMBus Support Allows for Operation with or

without Host) and bq40z50 (bq40z50evm board, Supports Two-Wire SMBus v1.1 Interface).
This circuit make charge, discharge and calibrate is successfully, but I facing the problem:
Charge work only if I run BatteryManagementStudio (ver 1.3.31) and make smbus connection through EV2300 adapter or read any

register bq40z50 in external embedded system (watch -n 1 'i2cget -y 1 0x0b 0x09 w').
If I exit BatteryManagementStudio or stop "ping" bq40z50 via i2cget from smbus, then after about 5 seconds charge is switch off.

Repeated start BQStudio or run i2cget activate the continuation of the charge..
I check activity smbus (have pullup 10kom) from oscilloscope. If no appeals in registers bq40z50, smbus have high level and

periodically (aprox 10..40 secs) I see several bytes. Because ltc4100 is slave, this bytes send from bq40z50 (probably

broadcast), but charge is not run..

about hardware:
external PSU (19V, 3A)
pack of fresh Li-ion accumulators (3S configuration)
custom board with ltc4100 (schematic typical from data sheet)
bq40z50emv (ver 3.1r) with bq40z50 (firmware 0x12 build 0x18)

about soft:
NR=1 (no removable mode)
I download fresh BQStudio (1.3.34) - problem is not resolved
I try switch on/off options:
broadcast, sleep mode, bus timeout delay - no success :(

My question: for standalone charger enough bq40z50 and smartcharger chip? or need external active host in role master?
or that I missed?

Thanks,
Jury

  • 0
    TI__Genius 10235 points
    Make sure to set the SLEEPCHG bit in FET Options to 1. This will keep the PCHG or CHG FET on during sleep and allow the charger to wake up the device. Otherwise, communication will be necessary, which is probably why charging is only working for you when bqStudio is running.
  • 0 in reply to Chase7071949597
    Intellectual 765 points

    Thanks for replay..

    I try 4 combinations (after each set combination of bits I reset bq40z50 from BQStudio):

    sleep=0; sleepchg=0;

    sleep=0; sleepchg=1;

    sleep=1; sleepchg=0;

    sleep=1; sleepchg=1;

    and measure value of voltage at pin CHG on board bq40z50emv. For all combination of bits I see for charge 23V and 6V for lose charge.

    ps: I try switch on/off bit CHGFET - no success

    For example my current setting: