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Unused DRV8313 Comparator

Derek King1
Intellectual 365 points
Other Parts Discussed in Thread: DRV8313

I'm not using the comparitor on the DRV8313.   Most places recommend connecting inputs to different potentials to produce a stable output state.

http://www-k.ext.ti.com/srvs/cgi-bin/webcgi.exe?Company={5761bcd8-11f5-4e08-84e0-8167176a4ed9},kb=analog,case=9753,new

Unfortunately, I'm routing a small PCB and connecting all comparitor pins to ground would save a bunch of space.    

Is there enough hysteresis on the comparator to produce a stable output when inputs are tied to same potential?  

Also, its it possible to also tie the comparator open-drain output to ground, or should I leave it floating?

  • 0
    TI__Mastermind 26065 points

    Hi,

    You are right it is always good to let the input at a state to produce stable output of a comparitor or OpAmp.

    the comparitor of DRV8313 do not have special hysteresis design which means nearly no hysteresis at all. So you'd better place the two inputs at different level.

    Also, as we have a open drain MOSFET to the compartitor's output It will be no problem to tie the open drain to ground. In my opinion, it is better than float.

    But above setting is just better way, it is not means there must be problems if you don't do this. if you put all the two input and the output to GND, should be fine because there will be little current noise even compare to the comparitor's normal working condition.

    Thanks.

    Wilson

  • 0 in reply to Wilson Zuo
    TI__Guru 55655 points

    Derek,

    It can also be noted that the comparator is isolated from the remainder of the chip.  So, functionally the output of the comparator doesn't effect functionality of the motor drive.