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BQ25756: config

zhang ping
Genius 3835 points
Part Number: BQ25756
Other Parts Discussed in Thread: TPS26750,

Tool/software:

We are developing a 240W charging and discharging point using the TPS26750+BJ25756 solution, with a type-c interface and Horizon as the main controller. We will use PCIe to extend USB 3.0 and connect TYPE-C for communication. At the same time, we need to charge the internal battery, which has 11 strings and is approximately 46.2V. We also need to support 240W discharging, which is based on the PD protocol. We need to understand the configuration issues.
1. Is the current configuration as shown in the picture reasonable?
2. What is the default setting when EEPROM is not burned?
3. At present, it can be charged, but the output can only be given to one device; Is there any way?
4. Do you have any files for the configuration of PD for us?

04_PD_Charger.pdf

05_PD_CTL.pdf

  • 0
    TI__Mastermind 31400 points

    Hello Zhang,

    Thanks for being patient with this. I'm looping in the USB-PD application experts to help with this problem.

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    TI__Mastermind 37855 points

    Hi Zhang,

    zhang ping said:
    1. Is the current configuration as shown in the picture reasonable?

    Yes, those settings seem fine from the PD controller perspective.

    zhang ping said:
    What is the default setting when EEPROM is not burned?

    The "default" setting depends on the power up state.

    If powering from VBUS in a dead battery state, the default setting is the dead battery state, which changes depending on the ADCIN configuration.

    If powering form VIN3V3, the default setting is safe mode. No sourcing, and an Type-C sink default contract (non-pd) can be negotiated.

    The PD controller is not intended for use without an image loaded on boot, whether it is from the EEPROM or loaded by an I2C host using the PBMx flow. 

    zhang ping said:
    3. At present, it can be charged, but the output can only be given to one device; Is there any way?

    I'm not sure what you mean by this. By output, do you mean the sink voltage? Is there any way to what? You could potentially connect the VDD rail to power other parts of the system.

    zhang ping said:
    4. Do you have any files for the configuration of PD for us?

    No, the configuration you shared in the screenshots should be fine. We would not have anything different to share.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    Genius 3835 points

    Please check if our configuration is correct? The current phenomenon is that it can be charged, but not discharged. We purchased a 46.2V battery pack;
    Scenario of inserting a USB flash drive when there is a load:
    1. The voltage of CC1 or CC2 is around 0.3V (pulled down by the USB sink resistor)
    2. PP-IN is low
    Could you please help analyze where the problem is?

    SCHEMATIC1 _ 05_PD_CTL.pdf

    SCHEMATIC1 _ 04_PD_Charger.pdf

  • 0 in reply to zhang ping
    TI__Mastermind 37855 points

    Hi Zhang,

    As mentioned above, I don't see any issues with the configuration.

    Could you provide a log of the following signals when the flash drive is conncted?

    1. CC line
    2. VBUS (VDD_PD)
    3. PPHV (VDD_PW)
    4. VBUSLV(VBUS_PD)

    In addition, could you get an I2C log of the I2C line between the TPS26750 and BQ25756 on power up and during the flash drive connection.

    Do you have a PD analyzer or anything that can be used to debug PD cc line messaging?

    We need to determine if the PD controller is seeing the attach, and what steps it takes after to program the BQ and source 5-V.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    Genius 3835 points

    At present, there is a problem where the device (such as a 5V powered switch) is plugged in with electricity during discharge scenarios. This phenomenon is normal. When the external power is turned off and the device loses power, the phenomenon is also normal. When the external power is turned on and the device is powered on again, the PD interface does not discharge externally. Can you help analyze the reason?

  • 0 in reply to zhang ping
    TI__Mastermind 37855 points

    Hi Zhang,

    Can you obtain a PD log of the behavior when you repower the device? Do you see VBUS go to 5-V?

    If you unplug and replug the device, does the TPS26750 start sourcing/discharging?

    Thanks and Regards,

    Chris