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Original question:

BQ25713: Cannot read chip ID when debugging the charging function

BQ25713: Cannot charge after the device is turned off

Lumina Gui
Genius 3690 points
Part Number: BQ25713
Other Parts Discussed in Thread: BQ25790, BQ25792

Hi Sir,

Our tablet project using the BQ25713 for battery charge design, but now we have encountered a serious problem. That is, after the tablet is turned off, I2C cannot communicate with BQ25713, resulting in failure to charge. 

I want to know the cause of this problem and whether it can be solved by update the software or hardware. If more information was needed, pls tell me and I will provide them ASAP.

Thanks,

Best Regards

  • 0
    TI__Genius 11385 points

    Hi Gui,

    Thanks for reaching out.

    Let me ask a few questions to sync:

    1. What do you mean that the tablet is turned off? Do you mean that the battery is removed? Is an adaptor present?
    2. Are you able to communicate via I2C under normal conditions?
    3. Please describe your input (voltage level) and output conditions (battery cell count setting, current battery voltage, etc.). Any additional info that is helpful to debug would be nice as well.

    If either an adaptor or a battery is present, you should be able to communicate with the IC via I2C.

    We also have the EVM for evaluation and compare results if you are interested.

    https://www.ti.com/store/ti/en/p/product/?p=BQ25713EVM-017 

    Thanks,

    Peng

    *If my answer solves your question, please press "This Resolved My Issue" on the thread.  

  • 0 in reply to Pengzhao Zhu
    Genius 3690 points

    Hi Peng,

    Regarding your question, my reply is as follows:

            Q1: What do you mean that the tablet is turned off? Do you mean that the battery is removed? Is an adaptor present?

    A: The tablet is turned off means all of the system power were closed. However, the battery is not removed and the adapter is normally connected.

            Q2: Are you able to communicate via I2C under normal conditions?

    A: Yes. I2C communication works well when the tablet in normal boot conditons.

            Q3: Please describe your input (voltage level) and output conditions (battery cell count setting, current battery voltage, etc.). Any additional info that is helpful to debug would be nice as well.

    A: The input voltage is 12V and the output is 8.4V (2-cell battery).

    Due to the design of our products, all system power supplies will be turned off after the device is shut down. At this time, the charging IC cannot communicate with the system chip (Rickchip platform)  through I2C. We want to know is there any way to realize that the charging IC can be charged independently without I2C communication.

    Thanks,

    Best Regards

  • 0 in reply to Lumina Gui
    TI__Genius 11385 points

    Hi Gui,

    I see what you are asking. BQ25713 is an IC that requires host intervention at all times so I2C is needed to initiate charging cycle. If you unplug the adaptor, CHRG_OK goes low, the ChargeCurrent register will reset to default. However, you should still have system voltage as the battery is still connected. If your application allows, you can take advantage of that.

    There are standalone ICs in our portfolio that can potentially support your need.

    https://www.ti.com/power-management/battery-management/charger-ics/products.html 

    There are also BQ25790 and BQ25792 (both buck boost parts). These are not totally standalone parts and I haven't work with them much, but it seems like they have a "PROG" pin that you can take advantage of. If you are interested, I can get a colleague who is more familiar with these parts to help you out.

    I would recommend getting an EVM to evaluate first regardless of which path you decide to move forward towards.

    Thanks,

    Peng

    *If my answer solves your question, please press "This Resolved My Issue" on the thread.  

  • 0 in reply to Pengzhao Zhu
    Genius 3690 points

    Hi Peng,

    Thanks for your suggestion, and we will consider it carefully

    Best Regards