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BQ25155: Some question about BQ25155

Lumina Gui
Genius 3620 points
Part Number: BQ25155
Other Parts Discussed in Thread: BQ21061

Hi All,

I have some question about BQ25155 when I do some battery charger design, as follows:

Q1: Did VDD output can be turned off the output through I2C after the Vin input is disconnected? What is the voltage of VDD at this time?

Q2: CE is the charge enable pin, can i drive it to low all time and don't connect it to host?

Q3: I2C uses the system power supply pull-up design. Whether I2C will stop working when VIN input was disconnected, and will there be leakage at the moment

Q4: Did VIO can be connected to external input directly?

Q5: If LP pin pulled down directly without connecting to the host, did BQ25155 automatically enter low power mode after VIN is disconnected?

Q6: INT is used as an interrupt pin. How many types of interrupts are there?

Q7: If the LDO pin is not used in the design, can it be nc, or the internal can be shut down through I2C. Did LDO still working after vin is disconnected, and what is the leakage current?

Q8: What is the main difference between BQ25155 and BQ21061?

Thanks a lot

Kind Regards

  • 0
    TI__Mastermind 23410 points

    Hi Lumina,

    Lumina Gui said:
    Did VDD output can be turned off the output through I2C after the Vin input is disconnected? What is the voltage of VDD at this time?

    The VDD output will remain on in all power states except for state mode.

    Lumina Gui said:
    CE is the charge enable pin, can i drive it to low all time and don't connect it to host?

    Yes, this is fine. 

    Lumina Gui said:
    I2C uses the system power supply pull-up design. Whether I2C will stop working when VIN input was disconnected, and will there be leakage at the moment

    I2C will only work when VIN is disconnected when in Active Battery mode. You can expect the following quiescent currents when in active battery mode. I've also added low power mode.

    Lumina Gui said:
    Did VIO can be connected to external input directly?

    It is intended to be connected to an external system IO supply. If there is none available, you can connect it to the VDD Pin.

    Lumina Gui said:
    If LP pin pulled down directly without connecting to the host, did BQ25155 automatically enter low power mode after VIN is disconnected?

    The device will enter low power moded when /LP is low, VIN < VUVLO, /MR pin is high, and all I2C and interrupts have been completed. 

    Lumina Gui said:
    INT is used as an interrupt pin. How many types of interrupts are there?

    There are quite a few, you can find a list in Table 5 of the datasheet. You can choose to mask them in the Interrupt Mask registers. 

    Lumina Gui said:
    If the LDO pin is not used in the design, can it be nc, or the internal can be shut down through I2C. Did LDO still working after vin is disconnected, and what is the leakage current?

    You can connect it in the LDOCTRL register. 

    Lumina Gui said:
    What is the main difference between BQ25155 and BQ21061?

    The main difference is the BQ21061 has no ADC.

  • 0 in reply to Anthony P Pham
    Genius 3620 points

    Hi Anthony,

    Thanks a lot. 

    For your answer for Q3, I don't quite understand.

    You said that I2C will only work when VIN is disconnected when in Active Battery mode. But how BQ25155 realize the I2C Programmable regulated system voltage (PMID) and battery voltage and current tracking function when battery charging.

    Regards,

    Lumina

  • 0 in reply to Lumina Gui
    TI__Mastermind 23410 points

    Hi Lumina,

    If the device is only being powered by the battery, there are three different modes available: ship mode, low power mode, and active battery mode. You can find more specific information about these states in the datasheet but feel free to continue asking questions here.

    In low power mode, the device is being powered by the battery but still active, the device will still have active power rails and operate in a low power state (or off). I2C is a function that is not available in low power mode. 

    To avoid confusion, I2C does work in adapter mode. I had said "only" in reference to the device operating in a battery powered state.