Why are N-Channel mosfets used here on the battery gauge lines?

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  • caphair
    Badcaps Legend
    • Nov 2011
    • 1249
    #1

    Why are N-Channel mosfets used here on the battery gauge lines?

    This is from the iPhone 10, previous models didn't have mosfets on the gauge lines so I'm wondering why they're used now.

    Is it so the phone can't boot with just a voltage present from external supply with gauche lines or?

    (First attachment is from the iPhone 10 and the next is from an iPhone 6s)
    Attached Files
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    • redwire
      Badcaps Legend
      • Dec 2010
      • 3910
      • Canada
      #2
      Re: Why are N-Channel mosfets used here on the battery gauge lines?

      I would say the iPhone 10 MCU is lower I/O voltage at 1.8V
      The two Rohm RV1C002UN MOSFETs are used as level-translators for the battery pack serial comms.
      They convert from 3.7V-4.3V serial data from the battery management IC down to 1.8V for the MCU I2C port, so they can talk to each other.

        Comment

        • caphair
          Badcaps Legend
          • Nov 2011
          • 1249
          #3
          Re: Why are N-Channel mosfets used here on the battery gauge lines?

          Thanks. Is a level translator the same as level shifting?

            Comment

            • redwire
              Badcaps Legend
              • Dec 2010
              • 3910
              • Canada
              #4
              Re: Why are N-Channel mosfets used here on the battery gauge lines?

              Yes, they mean the same thing.

                Comment

                • japlytic
                  Badcaps Legend
                  • Oct 2005
                  • 2086
                  • Australia
                  #5
                  Re: Why are N-Channel mosfets used here on the battery gauge lines?

                  I've seen N-channel MOSFETs on power tool battery packs which serve as an overdischarge and overcurrent protection function.
                  My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.

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