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LMV7235: Comparator threshold detection implementation

Vishal A1
Intellectual 540 points
Part Number: LMV7235

Hi,

We are using "LMV7235M5/NOPB" comparator in our design for threshold detection. I.e Vref = 1.3V and when Vin is above 1.3V ,the comparator saturates to Vdd which is 3.3V(High). When Vin goes less than 1.3V ,the comparator saturates to negative(low). I have attached the schematic implementation of the same .Kindly verify and confirm if it is correct.

I have added a series 10k resistor(R443) to the Non inverting terminal for input impedance. Please let me know if the value does not affect the Vin and suggest a suitable resistor value if possible.  Also what will happen if we remove that resistor?Does the circuit works fine without any malfunction?Kindly advice on this!

  • 0
    TI__Mastermind 24400 points

    Vishal

    I was not able to see the schematic that you attached but what you have described is correct if you connected VREF to the inverting pin and VIN is connected to the noninverting input.  We refer to this a noniverting configuration.  Adding a series resistor such as a 10k resistor is nice when an input comes from off board because it can protect the input stage against voltages outside of the operating range of the comparator by acting as a current limit.

    Adding or removing the 10k resistor should have little to no impact on your circuit.  

    Chuck

  • 0 in reply to Chuck Sins
    Intellectual 540 points

    Hi Chuck,

    Thank you for the confirmation.