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BQ24038: changed charge current after recovered DPPM mode

Dexter Choi
Expert 2795 points
Part Number: BQ24038
Other Parts Discussed in Thread: EV2400

Dear Sir,

When V(dppm-reg) is same Battery voltage. charge current is changed from 343mA to 450mA after recovered DPPM mode.

please check it and let me know that how to fix this issue.

V(dppm-reg) = 3.795V

Charge current : 348mA

Charge mode : USB Mode (PSEL : Low)

When BATTERY VOLTAGE is 3.314V. Charge current is OK.

When BATTERY VOLTAGE is 3.741V. Charge current is changed from 343mA to 450mA after recovered DPPM mode.

please refer to the schematic.

BQ24038.pdf

  • 0
    TI__Mastermind 22280 points

    Hi Dexter,

    Would you be able to provide the following information so I may further diagnosis the issue?

    • Voltage at ISET2 waveform with current at DPPM recovery
    • Voltage at ISET1 waveform with current at DPPM recovery
    • In your scope shot that you've provided, what is the output voltage on recovery? 

    Would you be also try exiting DPPM but with IOUT being non-zero? 

  • 0 in reply to Anthony P Pham
    Expert 2795 points

    Dear Anthony,

    This issue happen same with EVM.

    please refer to the attached file.

    Setting

    1. Rset : 3.05K
    2. Rdppm : 33K
    3. PSEL : Low

    BQ24038-EVB_charging test_20201019.xlsx

  • 0 in reply to Dexter Choi
    TI__Mastermind 22280 points

    Hi Dexter,

    Thank you for the information, I will get back to you in the next few days. 

  • 0 in reply to Anthony P Pham
    TI__Mastermind 22280 points

    Hi Dexter,

    Apologies for the delay. 

    With PSEL being low, you are prioritizing USB power. With ISET2 appearing HIGH, this is applying a 500mA current limit to USB power and this will be applied to the battery if that current is available. 

    In the image provided containing ISET1 and ISET2 in the case where the charge current changes at 3.7V battery, there is a concern. The voltage at ISET is prportional to charge and so should be higher than it was previously but is instead lower. This should mean that the charge current should be lower than it was when ISET1 is 2.4871 V. 

    To diagnose further, it'd be benefitial to answer the following questions:

    • What is the status of /ACPG and /USBPG pins? Is this occurring when AC power and USB power are active?
    • Does this behavior still occur if you increase V(dppm-reg)?
    • How is the output battery current being measured?
    • What is the purpose of the changing current programming? Is it simply to differentiate a USB vs AC current charge?

  • 0 in reply to Anthony P Pham
    Expert 2795 points

    Dear Anthony,

    This issue happen TI's EVM.

    please check below answer.

    • What is the status of /ACPG and /USBPG pins? Is this occurring when AC power and USB power are active?
      • #ACPG/#PG : Low
    • Does this behavior still occur if you increase V(dppm-reg)?
      • Changed V(dppm-reg) to 4.3V (Rdppm: 37.4Kohm), and the test result is the same.
    • How is the output battery current being measured?
      • Check by connecting to Battery Fuel Gauge EVM (EV2400)

    • What is the purpose of the changing current programming? Is it simply to differentiate a USB vs AC current charge?
      • 2 type of battery are 510mAh and 700mAh, and it cannot exceed 0.5C of battery capacity when charging according to the cell spec.
      • Regardless of USB mode or AC mode, PSEL is always LOW.

    Thanks.

  • 0 in reply to Dexter Choi
    TI__Mastermind 22280 points

    Hi Dexter,

    With ISET2 HIGH and PSEL selected for USB mode, the charge current will be 500. What is the current outside of the 3.7 and 3.3 battery range?