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Original question:

BQ25125: STAT_0 STAT_1 = 11 Error Status When Setting ICHRG Higher than 70mA

BQ25125: BQ25125: STAT_0 STAT_1 = 11 Error Status When Setting ICHRG Higher than 70mA

Lucas Heitele
Prodigy 40 points
Part Number: BQ25125

Tool/software:

Hello,

I'm reopening the discussion on an issue I encountered with the BQ25125 battery charger IC. In my previous thread, I noted that the system works fine with ICHRG set to lower values like 20mA, but setting it higher causes an error where STAT_0 and STAT_1 both read 1 (binary 11).

Configuration:

  1. ILIM: 200mA
  2. CE (Charge Enable): 0 (Enabled)
  3. MRRESET: 5 seconds
  4. SYS VOUT: 2.5V
  5. VINDPM and MRREC: Disabled
  6. ICHRG:150mA (error occurs)

Register Values at 150mA (Error Occurs):

00> I: Register 0x00 (STATUS_AND_SHIP_MODE_CONTROL_REGISTER): 0xC5
00> I: Register 0x01 (FAULTS_AND_FAULTS_MASK_REGISTER): 0x00
00> I: Register 0x02 (TS_CONTROL_AND_FAULTS_MASKS_REGISTER): 0x88
00> I: Register 0x03 (FAST_CHARGE_CONTROL_REGISTER): 0xAC
00> I: Register 0x04 (TERMINATION_PRECHARGE_REGISTER): 0x0E
00> I: Register 0x05 (BATTERY_VOLTAGE_CONTROL_REGISTER): 0x78
00> I: Register 0x06 (SYS_VOUT_CONTROL_REGISTER): 0xAA
00> I: Register 0x07 (LOAD_SWITCH_LDO_CONTROL_REGISTER): 0x44
00> I: Register 0x08 (PUSH_BUTTON_CONTROL_REGISTER): 0x40
00> I: Register 0x09 (ILIM_BUVLO_CONTROL_REGISTER): 0x1A
00> I: Register 0x0A (VOLTAGE_BASED_BATTERY_MONITOR_REGISTER): 0x7C
00> I: Register 0x0B (VINDPM_TIMERS_REGISTER): 0x42

Register Values at 20mA (No Error Occurs):

00> I: Register 0x00 (STATUS_AND_SHIP_MODE_CONTROL_REGISTER): 0x41
00> I: Register 0x01 (FAULTS_AND_FAULTS_MASK_REGISTER): 0x00
00> I: Register 0x02 (TS_CONTROL_AND_FAULTS_MASKS_REGISTER): 0x88
00> I: Register 0x03 (FAST_CHARGE_CONTROL_REGISTER): 0x3C
00> I: Register 0x04 (TERMINATION_PRECHARGE_REGISTER): 0x0E
00> I: Register 0x05 (BATTERY_VOLTAGE_CONTROL_REGISTER): 0x78
00> I: Register 0x06 (SYS_VOUT_CONTROL_REGISTER): 0xAA
00> I: Register 0x07 (LOAD_SWITCH_LDO_CONTROL_REGISTER): 0x44
00> I: Register 0x08 (PUSH_BUTTON_CONTROL_REGISTER): 0x40
00> I: Register 0x09 (ILIM_BUVLO_CONTROL_REGISTER): 0x1A
00> I: Register 0x0A (VOLTAGE_BASED_BATTERY_MONITOR_REGISTER): 0x7C
00> I: Register 0x0B (VINDPM_TIMERS_REGISTER): 0x42

And the image of the chip integration:

When the charge current is set to 150mA for example, the error status appears, as seen by STAT_0 and STAT_1 being set to 1. At 70mA, the system functions without any issue.

I would appreciate any guidance or suggestions on why this issue occurs when increasing the ICHRG value beyond 70mA. If any additional information, such as the PCB layout or schematic, is required, please let me know.

Thank you for your time and support.

Best regards,
Lucas Heitele

  • 0
    TI__Genius 17925 points

    Hi Lucas,

    Do you have any load connected to the device output rails? This appears to me like the device is hitting its input current limit which will report a fault but does not have an ILIM stat or flag. You can try raising the ILIM setting to see if that resolves the behavior.

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    Prodigy 40 points

    Hi Juan,

    Thank you for your response.

    I do have a small load connected to the device's output rail: an nRF5340, which typically consumes around 5-6mA. Based on your suggestion, I increased the ILIM setting, and here are the updated register values after making that change:

    Register 0x00 (STATUS_AND_SHIP_MODE_CONTROL_REGISTER): 0xC5
Register 0x01 (FAULTS_AND_FAULTS_MASK_REGISTER): 0x00
Register 0x02 (TS_CONTROL_AND_FAULTS_MASKS_REGISTER): 0x88
Register 0x03 (FAST_CHARGE_CONTROL_REGISTER): 0xAC
Register 0x04 (TERMINATION_PRECHARGE_REGISTER): 0x0E
Register 0x05 (BATTERY_VOLTAGE_CONTROL_REGISTER): 0x78
Register 0x06 (SYS_VOUT_CONTROL_REGISTER): 0xAA
Register 0x07 (LOAD_SWITCH_LDO_CONTROL_REGISTER): 0x44
Register 0x08 (PUSH_BUTTON_CONTROL_REGISTER): 0x40
Register 0x09 (ILIM_BUVLO_CONTROL_REGISTER): 0x3A
Register 0x0A (VOLTAGE_BASED_BATTERY_MONITOR_REGISTER): 0x64
Register 0x0B (VINDPM_TIMERS_REGISTER): 0x42

    After raising ILIM, the error with ICHRG still persists. The STAT_0 and STAT_1 bits remain set to 1 (error status). The load on the output rail remains minimal (~5-6mA), so I don't expect it to be triggering a significant input current limit.

    Do you have any further suggestions on what else might be causing this issue?

    Thank you again for your assistance!

    Best regards,
    Lucas Heitele

  • 0 in reply to Lucas Heitele
    TI__Genius 17925 points

    Hi Lucas,

    It is unexpected that with only a 6mA load that you would be hitting ILIM, though this behavior does seem to be associated with the increased charge current.

    Can you please provide waveforms of VIN, INT, PMID, and VBAT at pin during both scenarios (ICHG = 20mA vs ICHG = 150mA). If possible capturing IIN and IBAT waveforms could provide some helpful insights.

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    Prodigy 40 points

    Hi Juan,

    thank you for your reply. Do you need the waveforms during specific events or just during normal charging, when the error occurs?

    So like this, for INT ar 150mA setting, for example:

    If yes, i will provide the rest of the waveforms. If you need it different, let me know :-)

    Best regards

    Lucas Heitele

  • +1 in reply to Lucas Heitele
    TI__Genius 17925 points

    Hi Lucas,

    If you can capture the behavior as charging is enabled so we can see the rail behaviors before charging, across the transition, and during charging then we might be able to get a better idea of what's going on.

    One thing I did notice is that the VINDPM flag seems to be active, this typically indicates that the input source is being overloaded and current limited as a result. Do you know how large your SYS, PMID and LDO loads are during this period? It looks like the input source is not able to provide sufficient current for both the system load and the battery charging. What is the expected VIN voltage and VIN current capability?

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    Prodigy 40 points

    Hi Juan,

    Thanks for your help regarding the VINDPM threshold. Lowering the threshold solved the issue I was experiencing.

    However, I noticed a voltage drop across diode D201: I'm measuring 5.1V before D201 and 4.6V on the load side after it. I believe this is due to the forward voltage drop of the diode, which could be in the range of 0.5V.

    I suspect this is normal behavior for the component, but I wanted to check if this could affect the BQ25125 operation in any way, or if there are additional considerations I should keep in mind.

    Thanks for your support!

    Best regards,
    Lucas

  • 0 in reply to Lucas Heitele
    TI__Genius 17925 points

    Hi Lucas,

    A VIN of 4.6V shouldn't be an issue as long as your battery regulation voltage isn't any higher than Vslp below 4.6V. This should be fine as long as your VINDPM is set to an appropriate voltage and further voltage drop is not expected.

    Best Regards,

    Juan Ospina