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DRV8874-Q1: Status of Charge Pump

Josef Warta
Expert 4060 points
Part Number: DRV8874-Q1
Other Parts Discussed in Thread: DRV8874

Hello Team, one question from customer:

Is the charge pump active when OUT1 and OUT2 are tri-state (means in-acitvie) ?

Many Thanks

Josef

  • 0
    TI__Genius 9025 points

    Hi Josef,

    Who is the customer and what is their application? The charge pump will still be active even if the outputs are HI-Z'ed. What is the reasoning behind this question?

    Best,

    Keerthi

  • 0 in reply to Keerthivasan Kumanan
    Prodigy 60 points

    Hi. We were thinking about to use the charge pump of the DRV8874 to control a transistor which is in series with OUT2. The purpose of this transistor is to avoid a current flow backwards through the bulk diode of OUT2. Between OUT2 and the transistor, we have a shunt to measure the current, but this current measurement has to be calibrated. For this calibration process we need to put OUT2 in HI-Z'ed but we still have to activate the transistor. 

  • 0 in reply to Georg Großmann
    TI__Mastermind 21980 points

    Hey Georg,

    Agreed with Keerthi, the charge pump will still be active when OUTx is Hi-Z.  So sounds like that should work for your system.  I recommend seeing if you can modify a DRV8874-Q1EVM and testing it out there, seems like it should work.  

    FYI, the body diodes of our FETs are rated for the same amount of current as the FET itself, so this type of extra protection is not typically necessary. 

    Best,

    Jacob