• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Subscribers 65 subscribers
  • Views 472 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.

Original question:

BQ25616JEVM: [Offline Support Request] BQ25616J 　　　 Inquiries about full charge detection

BQ25616JEVM: This is a continuation of the question about the full charge detection of the BQ25616J that I inquired about last time.

Masahiko Kodama
Prodigy 40 points
Part Number: BQ25616JEVM


This is a continuation of the question about the full charge detection of the BQ25616J that I inquired about last time.

Instead of asking the question on BQ25616JEVM, when BQ25616J is mounted on this board, built into the product,

and an environmental test is performed, the behavior at the end of charging is different at environmental temperatures

of 28 ° C and 30 ° C, and 30 ° C (or higher) Then, the battery should be released as it is fully charged, but the battery

voltage does not drop as expected, probably due to the fact that a minute current (?) is flowing, which is a problem.

thank you.

  • 0
    TI__Genius 10240 points

    Hi Kodama-san,

    Do you mean that BQ25616J charging termination behavior seems different at Ta=25C and Ta=30C? When you made the test comparison, did you have the exact same setup because the PCB/wire impedance from the charger IC to the battery and the battery internal impedance depending on the battery age contribute the voltage drop. It would be great if you can provide some data and drawing to show the difference. 

    Regards,

    Eric

  • 0 in reply to ezhao
    Prodigy 40 points

    Attached is the battery voltage graph during charging and discharging when the environmental test was performed successively (first at 28°C and then at 30°C).

    (It cannot be imported in "insert → image". I will consult with Mr. Yoshida of TIJ.)

    The BQ25616J settings are 400mA input limit, 400mA charge current, and 4.1V charge termination voltage.

    thank you.

  • 0 in reply to Masahiko Kodama
    TI__Prodigy 660 points

    Kodama-san, Zhao-san,
    Please refer the attached image.

    Regards,
    Yoshida

  • 0 in reply to Satoshi Yoshida
    TI__Guru 59101 points

    Kodama-san, Yoshida-san,

    1. Did you measure the same point on the same board for 28C and 30C measurements?

    2. Did you measure the BAT pin voltage of the BQ25616J or the battery terminal voltage?

    3. Besides the charge voltage, could you please also add the charge current on the graph?

    Please note that the voltage across the parasitic resistance (resistance on the charging path such as routing, connector, sensing resistor etc.) and the battery internal resistance also changes after the charge termination when the charge current drop to 0A.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 40 points

    I didn't change the measurement environment,

    just turned on/off the charging adapter and changed the temperature of the constant temperature bath.

    A1: Yes.　I haven't touched the measurement environment at all.

    A2: yes.　The battery voltage is recorded.

    A3: no.　  We have not measured the charging current.

    Graph description:

    1: Set the constant temperature bath to 28°C.

    2: Turn off the adapter and discharge the measurement set (stops working at 3.0v)

    3: Turn on the adapter and charge

    4: After confirming the drop in battery voltage due to full charge, Set the constant temperature bath to 30°C.

    5: Turn off the adapter and discharge the measurement set (stops working at 3.0v)

    6: Turn on the adapter and charge

    7: Even if the time for full charge has passed sufficiently, No clear voltage drop seen at 28°C

    In order to measure the current without affecting the charging environment,it is necessary to extend the wire from the battery and use a Tektronix current probe. In this measurement, we did not take such measures.

    What I'm worried about is how to deal with unused pins. Since USB system etc. are not used, D+, D- and ACDRV are open and OTG is pull-down.

    Also, the input current limit is set to 400mA, so is there any problem? "Will these symptoms occur?" "I'm curious."

    (Because the power for charging is by contactless power supply [5v], and the transmission current is only about 400mA.)

    thank you.

  • 0 in reply to Masahiko Kodama
    TI__Mastermind 22690 points

    Kodama-san,

    We are still looking into this and will get back to you with an update.

    Regards,

    James

  • 0 in reply to James Steenbock
    TI__Guru 59101 points

    Hi,

    Please visit https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/993268/bq25611d-bq25611d-schematic-review/ for BQ2561X: Schematic Review and PCB Layout Design Tips.

    1. It is ok to lease D+/D- pins open so that the input current limit is set by ILIM pin. 

    2. The acceptable range for ILIM current is 500 mA - 3200 mA. 400mA is out of the range.

    3. The input power should be enough to support the battery charging and SYS load.

    4. How can you tell whether the charge is terminated without the charge current information?

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 40 points

    We chose BQ25616J for the charging circuit part of the set we developed this time because

    1: In the explanation on the first page of the BQ25616J data sheet, ” Single input supporting USB input, high-voltage adapter, or wireless power”

    It is written, and on page 3, ”The device supports a wide range of input sources, including standard USB host port, USB charging port, USB compliant high voltage adapter and wireless power.”

    This is because there was a description about contactless power supply.

    2: Since the charging system of the battery and the operating power supply of the set are distinguished, When the battery is fully charged even when the set is in operation, charging is terminated and the battery is released,thereby reducing the load on the battery.

    As I mentioned before, I was able to set the input current limit to 400mA, which is outside the setting range, so I'm using it as is, but if the problem I'm having now is normalized, I'd like to set it to 500mA. I will consider changing it and trying it.

    In the set under development, the charging current is not monitored by the microcomputer. Judgment of full charge is based on the state of the STAT pin.

    thank you.