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BQ40Z80: MOSFET drive charge pump

Stefan Kljakic
Prodigy 20 points
Part Number: BQ40Z80

Hi all,

I read the datasheet of BQ40Z80, and I could not find any explicit info about charge pump gate current. There are only some timing info and voltage avalible but nothing about current.

I would like to use NVMTS0D4N04CTXG (non logic level version) MOSFET with high input capacitance but not sure how slowly will it turn on/off and if it will be fully opened and closed.

Best regards,

Stefan

  • 0
    TI__Genius 11770 points

    Hello Stefan,

    You can estimate the drive strength from the given rise/fall times and capacitance. Using the equation:

    I = C * dv/dt

    But you really don't need to crunch the numbers, you can just use the fact that they have a linear relationship to estimate the rise time while ignoring the drive current. The datasheet says that you will have a typical rise time of 200us with a 4.7nF input capacitance, so with your 16.5nF FET, I would expect a rise time of roughly 700us (about 3.5 times). I would expect fall time to be more like 140us using the same reasoning. 

    thanks,

    Alex M.