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BQ76952: BQ76952 high-side FET driver charge pump current capability

Aleksandar Lazarov81
Prodigy 220 points
Part Number: BQ76952

Hi all,

We are considering using the BQ76952 in an upcoming BMS development and I'm interested to know what is the current delivery capability of the integrated charge pump?

Kind regards,
Aleks

  • 0
    TI__Genius 10830 points

    hi Aleks,
    I suggest you go thru the app note specific on FETs: here. 

  • 0 in reply to David Hien
    Prodigy 220 points

    Hi David,

    Thanks for the feedback. I know this app note, and I went through it again. Unfortunately there is no answer on the current capabilities of the charge pump (current that can be supplied towards the gates of the FETs). Is there a number, or a range of numbers that you could give me?

    Thanks,
    Aleks

  • 0 in reply to Aleksandar Lazarov81
    TI__Guru 54715 points

    Hi Aleks,

    Calculating the charge pump current from the startup time of 100 ms for 11V with 470 nF with I = C x dV/dt, gives 51 uA, but in the figure 3-3 of  http://www.ti.com/lit/sluaa09 shows the voltage does not ramp linearly.  The charge pump is output through the CHG and DSG drivers which will have some resistive component, also not specified in the data sheet.  The normal load expected is a 10M ohm resistor on each driver for about 2.2 uA typical, but this load is not a test condition for the data sheet V(FETON_HI).  Expect to get only about 20 to 30 uA from the driver outputs before the voltage starts to drop significantly.  Be aware it is a charge pump and will have an inefficiency.