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BQ78350-R1: Do I need an additional charge chip or can I use this IC to charge the battery?

Paul K52
Intellectual 640 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76920, BQ78350, , BQ24617, BQSTUDIO

Hello,

Im want to connect the BQ78350 to the BQ76920, this should work fine, as the datasheet is telling me.

Now, I am thinking how I want to charge the battery. Im wondering, if I need another IC to charge the battery or if the BQ78350

wil do this by itself. In the datasheet of the BQ78350-R1 there is no pin where I can put the adapter current in. So I am thinking,

to use the BQ24617 for the charging process.

In this case all the charging configurations would be done with the BQ24617. (configuring the precharge-current, charge-current etc.)

What is your opinion about this? Would this work?

  • 0
    TI__Guru 54715 points
    Hi Paul,
    The bq78350-R1 is not a charger, it manages the measurement, protection and gauging of the battery. It can report the charge voltage and current for the battery, but some external charger must provide that voltage and current and develop them from the appropriate adapter source. The bq24617 appears to be a good choice. Please check the reference documents available for that part, if you need assistance search for posts with that part number or enter one if the relevant topic is not found.
  • 0 in reply to WM5295
    Intellectual 640 points

    Thanks for your Response.

    Refering to the Application Note on page 8, is is written, that there is a charging algorithm which can change the

    charging voltage and change the charging current (or in General: It can influence the charging process)

    How can the BQ78350 influence the charging process, if it doesnt support charging Features?


    For example: I would use the BQ76920 and the BQ78350 together, as recommended in the datasheets.

    For charging I want to use,the BQ24617. With this chip I would configurate the charging voltage, charging current. the charging algorithm and so forth.

    So why does the BQ78350 Support charging algorithm?

    Application Note: http://www.ti.com/lit/an/slua726/slua726.pdf

  • 0 in reply to Paul K52
    TI__Guru 54715 points
    Hi Paul,
    The application note you reference and the bq78350-R1 technical reference manual describe the charge algorithm as a set of voltages, currents and delays. See the technical reference for details. This information is available to the charger to read to determine what to provide to the battery. The bq78350-R1 does not charge the battery. As you indicate, it has no input for the power adapter.
  • 0 in reply to WM5295
    Intellectual 640 points

    Thanks for the Response.

    So, I want to use a charger-IC, which can receive data from the BQ78350. Then the BQ78350 should be connected with the charger via a communication path.

    There a two communication paths, which can be used from the BQ78350-> I2C or SMBUS.

    Refering to the datasheet of the BQ78350 on page 3, it is written that the I2C path, is "reserved" for the BQ76920. (It is explicitly written that I2C is for the BQ76920)

    The BQ78350 has a lot of commands, which can be used with SMBUS protocol, as I see from the Technical Reference of the BQ78350 on page 94.

    So I think that I have to connect the charger-IC via SMBUS to the BQ78350, which is the host controller, to be able to acess this command.

    At the end, the BQSTUDIO will be connected to the BQ78350 via SMBUS. With the Software I will Control and get Information of the battery. With the Software I will Control the charging algorithm. The Controlling Parameters for this, will be sent through SMBUS to the BQ78350 and the BQ78350 will send the Control paramters to the charger.

    So I just need a charger-IC, which can take Information via SMBUS. Is this correct?

  • 0 in reply to Paul K52
    TI__Guru 54715 points
    Hi Paul,
    See the simplified schematic on page 1 of the bq78350-R1 data sheet. The I2C is dedicated to communication with the monitor and can not be used for other communication. Nothing else should be on this I2C bus. SMBus is the path for external communication with the gauge.
    The bq78350-R1 will make available the charging parameters for the charger to read, or can broadcast them as described in section 16 of the technical reference manual.
    If your charger is "smart" it might support SMBus through a charger IC or an MCU, and may want to poll the battery for parameters or accept the broadcast depending on its architecture.