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BQ40Z60EVM-578: Excessive Charge Current in Charge Inhibit Mode as AC Adapter is applied

TK82
Intellectual 725 points
Part Number: BQ40Z60EVM-578
Other Parts Discussed in Thread: BQ40Z60

bq40z60 EVM-578

Excessive Charge Current (<3 Amp Charge Setting) occurs in Charge Inhibit Mode as the AC Adapter is applied (with a 2Amp Load).

The excessive current results into a Short Circuit Protection – Continuous (hiccup/trip & restart mode with auto recovery) when the AC Adapter is applied (XP Power VEF50US12).

 

We are experiencing excessive charge current (<3Amp Charge setting) when in Charge Inhibit Mode (<40C) as the AC Adapter is applied with a load of 2Amps on VSYS, J5 (the excessive current does not occur with no load).

 

The system turned Off (0 Amps on VAC, J1) when a 10Amp lab supply was used instead of the AC Adapter (with Short Circuit Protection) see ChargeInhibit_VAC_HiDrv_iAC_iBatt_Bad_8_10AmpSupply.bmp.

 

We are detecting the Charge Inhibit mode as described the Technical Reference Manual (Section 4.13) but the excessive current is a problem.

 

The experiments were done by replacing RT1 with a 10 turn 100K potentiometer (to dial in the temperatures.

 

Attached files include:

-          bq40z60_v0_15_build_21_2S6P_R0.05a.srec

-          Good/Bad log files

-          Good/Bad waveforms

Ch1 – VAC (J1)

Ch2 – HiDriv (pin 27)

Ch3 – iAC (current at J1)

Ch4 – iBatt (current at J3)

-          AC Adapter Power Supply Data Sheet

The battery is a 2S6P configuration (Li Ion Chem ID: 2012).

Any ideas of setting to change to reduce the excessive charge current??

Can CHG INHIBIT be disabled?

 

Thanks,

Tom

 ChargeInhibit_EVM.zip

  • 0
    Intellectual 725 points
    sorry, a couple of typo's

    should be:
    >3Amps (not <3Amps)
    >40C (not <40C)

    Excessive Charge Current (>3 Amp Charge Setting) occurs in Charge Inhibit Mode as the AC Adapter is applied.
    The excessive current results into a Short Circuit Protection – Continuous (hiccup/trip & restart mode with auto recovery) when the AC Adapter is applied (XP Power VEF50US12).

    We are experiencing excessive charge current (>3Amp Charge setting) when in Charge Inhibit Mode (>40C) as the AC Adapter is applied with a load of 2Amps on VSYS, J5 (the excessive current does not occur with no load).
  • 0 in reply to TK82
    Intellectual 725 points
    opps, more typo's

    got Ch3 & Ch4 Description backwards....
    should be:
    o Ch1 – VAC (J1) - Yellow
    o Ch2 – HiDriv (pin 27) - Green
    o Ch3 – iBatt (current at J3) - Blue, (Not iAC (current at J1)
    o Ch4 – iAC (current at J1) - Red, (Not iBatt (current at J3)

    T
  • 0 in reply to TK82
    Intellectual 725 points
    more info (hopefully, to help understand all the data)..

    All ‘Good’ files were recorded at 25C.
    All ‘Bad’ files were recorded at >40C (Charge Inhibit Mode).

    Notes:
    Ch1 (VAC) was not connected on the following files (indicates 0V).
    ChargeInhibit_VAC_HiDrv_iAC_iBatt_Good_1.bmp
    ChargeInhibit_VAC_HiDrv_iAC_iBatt_Good_2.bmp
  • 0 in reply to TK82
    TI__Mastermind 42535 points
    TK82,

    I will be looking into this. However it's going to take us some time to analyze all this. Expect to hear from me in about 10 working days or less with more questions or suggestions.
  • 0 in reply to Batt
    Intellectual 725 points
    Looks like the ‘ChgCurrReg’ is being set to 255 (max) in the ‘Bad’ log files,
    and the ‘ChgCurrReg’ is being set to 76 in the ‘Good’ log files (??).
    Any ideas??
  • 0 in reply to TK82
    Intellectual 725 points

    Hi,

    Setting the Max Current Register to 76 (I Limit = 3Amps, R CHR = 10 mOhms) solves to problem.....

    Data Memory/Advanced Charge Algorithm/Charger/MaxCurrentRegister.

    The default was 255 (10Amps) causing the  Short Circuit Protection – Continuous (hiccup/trip & restart mode with auto recovery) when the AC Adapter is applied (XP Power VEF50US12).

    this answer was very convoluted and criptic to find but it works ('or charge is inhibited for some reason').

    see attached references.

    thanks,

    Tom

    MaxCurrentRegister.docx