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DRV8935: how is the current sensed?

justifice zhou
Intellectual 400 points
Part Number: DRV8935

Hi,

in the datasheet I can't find how the current is sensed. Through low side FET or high side FET or both?

If I use it as four independent half bridge, is it true that no matter I connect the load from OUT to VM or OUT to GND, the current could be sensed within the device?

And if a resistor load is connected from OUT to GND, and the Itrip<VM/Rload, when IN=1(means high side FET on), the trip point will be reached soon, will the high side FET be turned off even if IN is still 1? Will it try to turn on high side FET again or the high side FET will be latched off? When will the high side FET be turned on again?

  • +1
    TI__Mastermind 20775 points

    Hi Justifice,

    The DRV8935 current sensing in done on LS FET only for current regulation using the VREF and comparator. So current regulation works only for HS connected loads. The mechanism of operation for current regulation and its sequence is described in the datasheet section 7.3.1 Bridge Control and Current Regulation. For a LS connected load there will be no current regulation possible. The load current for LS load will only be limited to VM/ RLOAD for resistive and inductive R & L loads and for BDC motor it will be limited by (VM-BEMF) / DCR when motor is running and spike up with large inrush current VM/DCR when motor is in standstill or stall. 

    Regards, Murugavel