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Original question:

BQ76PL455A-Q1: Power supply of the device

BQ76PL455A-Q1: Power supply of the device

Nicolás González
Prodigy 110 points
Part Number: BQ76PL455A-Q1
Other Parts Discussed in Thread: TMS570LS0714, BQ76PL455A

Hello,

I am trying to design a prototype of battery management system using this device BQ79PL455A-Q1 for the monitoring, and also the micro-controller TMS570LS0714 for the data management. The thing is that I want to use a DC/DC converter for this supply and I was wondering if the "TOP" pin from BQ455 device could serve as an input of the converter.

Another question, would you recommend any isolation in the converter? Should the GND of the circuit be referred to the battery negative?

Thank you for your time,

Regards!

  • 0
    TI__Genius 17440 points

    Hello,

    As long as your DC/DC converter can supply a voltage within the recommended operating conditions for the TOP pin and can supply enough current for the device, I see no issue with this approach. 

    What is your application? In the expected application for the BQ76PL455A, the device would draw power directly from the cells it monitors. In this setup the device ground is the same as the negative terminal of the battery. Unless you are trying to keep the BQ device on the low-voltage side of your board or its source voltage is higher than the BQ device can support, I don't see a need for isolation in the converter. 

    Best Regards,

    Kristin Jones

  • 0 in reply to Kristin Jones93
    Prodigy 110 points

    Hi,

    Thank you for your quick reply.

    Well, my application consist of a BMS for a 46 V lithium-ion battery pack. As I say, I'm using these two devices in a master-slave topology. Then, should I take for granted that the GND pins of the BQ455 are internally connected to the negative terminal of the bottom cell?

    Thank you!

    Nicolás

  • +1 in reply to Nicolás González
    TI__Genius 17440 points

    Hi Nicolas,

    The GND pins are not internally connected to the bottom channel, but it is expected that the GND of the device is connected to the negative terminal of the bottom cell.

    Best Regards,

    Kristin Jones

  • 0 in reply to Kristin Jones93
    Prodigy 110 points

    Thank you so much for your answer Slight smile