• State
  • Locked Locked
  • Replies 12 replies
  • Subscribers 64 subscribers
  • Views 446 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25720: BQ25720 Charger Register Mapping

Arpan Jain
Prodigy 100 points
Part Number: BQ25720
Other Parts Discussed in Thread: BQ40Z50-R1

In our project we are using battery charge controller IC, As per datasheet we have done some changes,

SMBUS Addr REGISTER NAME Set value from host
14h ChargeCurrent()  600h - 1536 mAmp
15h ChargeVoltage() 3138h - 12600 mVolt
3Fh IINHOST() 4100h - 3250 mAmp
3Eh VSYS_MIN 5C00h - 9200 mVolt

but after these changes battery is not charging yet. If anyone worked on it, help in setting the register value for now we are taking other register values as default.

Please guide us to make battery charging on.

Even if we are reading chargeCurrent after writing 600h, it fetches 0 value.

And for reading chargeVoltage after writing 3138h, it return 3830h and if we dont write and tried to fetch the chargeVoltage value so it returning 3138h

  • 0
    TI__Expert 3335 points

    Hi Arpan,

    The reason for battery not charging could be the CHRG_INHIBIT bit is set in register 12h or the charger is some fault condition such as VINDPM,IINDPM, SYSOVP etc. 

    Can you share the whole register map i.e. the values of all the registers?

    Best Regards,

    Munir

  • 0 in reply to Md Munir Hasan
    Prodigy 100 points

    We have write the register values which are mentioned above besides that i have disable the WDTMR_ADJ (13 & 14 Bit) to 00 of ChargeOption0 register (default value is E70Eh) -  final value to write is 0x870E.  And all other register values are taking as default.

    After these all changes, in logs we are able to read that voltage of battery is increasing to 12113 mVolt (total Cellvolage) from 10958 mVolt. But when check with the multimeter its still 0 volt.

    For reference FuelGauge we are using is bq40z50-R1 IC. and Register Mapping

  • 0 in reply to Arpan Jain
    TI__Expert 3335 points

    Hi Arpan,

    I wanted to know the value of all the registers, not just the one you mentioned. Since, you are reading a battery voltage from the log it looks like it is charging. However, in order to debug why multimeter is reading 0V, you need me provide me the whole register map. You need to provide me the values of all the registers in your charger, doesn't matter if they are taking default value or not. That will help me find any issue with charger. 

    And where are you connecting your multimeter? Which terminals you are connecting them to? Is the battery 0V from the start?

    Best Regards,

    Munir

  • 0 in reply to Md Munir Hasan
    Prodigy 100 points

    Address Command Registers Default Values Values From Logs
    12h
    ChargeOption0
    E70Eh
    870Eh
    14h
    ChargeCurrent
    0000h
    0600h
    15h
    ChargeVoltage
    3138h
    20h
    ChargerStatus
    0000h
    8000h
    21h
    ProchotStatus
    B800h
    B800h
    22h
    IIN_DPM
    4100h
    4100h
    23h
    ADCVBUS/PSYS
    CA00h
    24h
    ADCIBAT
    0000h
    25h
    ADCIINCMPIN
    0000h
    26h
    ADCVSYSVBAT
    0000h
    30h
    ChargeOption1
    3300h
    3300h
    31h
    ChargeOption2
    00B7
    00B7
    32h
    ChargeOption3
    0434h
    0434h
    33h
    ProchotOption0
    4A81h(2S~) 4A09(1S)
    4A81
    34h
    ProchotOption1
    41A0h
    41A0h
    35h
    ADCOption
    2000h
    2000h
    36h
    ChargeOption4
    0048h
    0048h
    37h
    Vmin Active Protection()
    006Ch(2s~4s)/0004h(1s)
    006Ch
    3Bh
    OTGVoltage
    09C4h
    3Ch
    OTGCurrent
    3C00h
    3Dh
    InputVoltage
    VBUS-1.28V
    3A40h
    3Eh
    VSYS_MIN
    5C00h
    3Fh
    IIN_HOST
    4100h
    4100h

    The above images were logs while reading respective register addresses from BQ25720. 

    NOTE:- All values read are default form the IC except:- 

    IIN_HOST - 4100h (3250 mAmp),, 
    VSYS_MIN - 5C00h (9200 mVolt),
    ChargeOption0 - 870E (set watchdog bits (14-13)  to 00),
    ChargeVoltage - 3138h (12600 mVolt)
    ChargeCurrent - 0600h (1536 mAmp)


    And the below image showing the FuelGauge (bq40z50-R1) logs.




    And for checking voltage with multimeter we are connecting the probes to Vbat and Gnd terminal.

  • 0 in reply to Arpan Jain
    TI__Expert 3335 points

    Hi Arpan,

    Thanks for the register map. The charge status register does not show any fault. It also shows that the charger is not neither in pre-charge nor in fast charge. Which leads me to question

    1. what is the battery voltage when you are attaching it to the charger? Are you attaching a battery with 0V?

    2. assuming that you are using a battery with non zero charge voltage and since you are measuring 0V from VBAT to GND, I believe the fuel gauge schematic needs to be checked by someone from fuel gauge support. We also need to check how the fuel gauge is connected to the charger.

    3. and this is a sanity check. You are charging a 12.6V battery with 1.536A charge current (according to the register map), your output power is at least 19.35W. Make sure that the input power is higher than this. Otherwise, charge current can drop to zero.

    Best Regards,

    Munir

  • 0 in reply to Md Munir Hasan
    Prodigy 100 points

    Hi Munir Hasan, 

    yes, Now i am using the charged battery which showing around 10.78 Volts with multimeter before plugin to system and with the same above registers value it goes to 11.40 volts but again its goes to discharges voltage. 

  • 0 in reply to Arpan Jain
    TI__Expert 3335 points

    Hi Arpan,

    Please share the schematic of your charger.

    Best Regards,

    Munir

  • 0
    Intellectual 500 points

    HI 

    Please find the attached schematic of battery charger

  • 0 in reply to Arpan Jain
    TI__Expert 3335 points

    Hi Arpan,

    I have reviewed the schematic. The charge controller part looks ok. However, the fuel gauge does not look like bq40z50-R1 and I cannot verify that schematic. Your schematic shows part number CW2015CSA. I am wondering if the resistor divider on the fuel gauge cell pin is responsible for discharge. 

    How long does it take for the battery to discharge from 11.4V to 0V? Is it very quick?

    Can you try charging the battery without the fuel gauge and see if there battery discharges as well? I would like to identify if the fuel gauge is causing this issue or not. Please, disconnect the fuel gauge from the charge controller and test battery charging.

    Best Regards,

    Munir

  • 0
    Intellectual 500 points

    Hi 

    The fuel gauge is with the battery pack pcm circuit board. We don't have any fuel gauge on mother board. So we can not be able to share the schematic for the fuel gauge.

    CW2015CSA is just kept as option on the motherboard. It is not mounted.

    Regarding the battery discharging, battery is not rapidly discharge. It slowly gets discharge.

    We will also check the battery discharge after disconnecting the battery fuel gauge communication pins.

    Except thisSweat smile, we also see that our of 3 batteries, two batteries are not able to come in working condition as these batteries are not getting charge. We are able to see the charging current across the resistor and voltage across the battery connector terminal but when we turn off the adapter, the battery is fully discharge. There is not voltage across the battery terminal.

    So please check this issue also and help us to resolve.

  • 0 in reply to Udesh Singla
    TI__Expert 3335 points

    Hi Udesh,

    Make sure that R1006 and R1010 on CW2015CSA is not connected to the battery. They are acting as a load on battery and may be responsible for slow discharge. Please test battery charge and discharge without this resistors connected to the battery.

    Best Regards,

    Munir