BQ24450 meaning of parameter Vpre_rev?

Discussion in 'General Electronics Chat' started by Timo D., Oct 21, 2011.

  1. Timo D.

    Thread Starter New Member

    Oct 21, 2011
    Hi all,

    this is maybe a silly question but I'm really not sure about this:
    The BQ24450 spec (same as UC3906) states a parameter called
    Vpre_rev: PRE-CHG reverse hold-off voltage
    For UC3906 it's called trickle bias reverse hold-off voltage.

    Now, what's the difference between that and the max. rated
    reverse voltage at PRE-CHG/trickle bias pin?
    I mean, if I could only apply up to 7V at this pin it would damage
    the device as soon as I remove Vin and have a e.g. 12V battery
    still attached. But this is how I understand this spec.

    Thanks in advance,
  2. #12


    Nov 30, 2010
    I don't think there is any difference, but I do see the cure in Figure 7.
    It's called Dext.
  3. Timo D.

    Thread Starter New Member

    Oct 21, 2011
    OK, let me summarize it:

    The max. rating states Vin-(PRE-CHG) = -32V

    Operation spec is:
    PRE-CHG (with Vin=0V, Ipre=-10uA) = 7V max.

    Does this simply mean that I have to assume a
    current much more than 10uA if I apply up to 32V
    at PRE-CHG, but the pin would withstand that?

    So adding Dext would solve both, minimum Ipre current
    at VBat > 7V?