2 Replies Latest reply on Mar 8, 2018 7:40 AM by user_65794679

    LPComp as a voltage supervisor

    user_65794679

      Hi

      I´m trying to do a typical voltage supervisor with a LPComp component.

      I want to test Vdd (Vplus, MCU power supply) voltage and when it drops below 3.1V go to Power Down (for example).

      But, if I put a reference in the other pin (Vminus ,resistor divisor) with the same Vdd it drops too, obviously, and condition is never given .

      There are any other way to do this?

      There is no have an internal Vref to do it?

      Thanks.

       

       

        • 1. Re: LPComp as a voltage supervisor
          zhxh

          Hi Cris,

           

          Have you considered to divided the VLOW, so you can use a lower VREF in the other pin. For example, if you want to test vdd when it drops to 3.0V, you can divide it by half, then you just need to give a 1.5V on the VREF and the VREF will not drop with the VDD.

          Regards,

          Owen

          • 2. Re: LPComp as a voltage supervisor
            user_65794679

            First, thanks for your response Owen.

            I have resolved it in another way.

            The problem is that voltage falls proportionally in both inputs so, even putting a divider, they never get to match.
            You´ll need a more stable internal reference.
            Thanks to another partner of the forum, if we put in IDAC we have a "fixed" (through a external fixed resistor) voltage reference source. We can make a more stable Vref which the condition is given.

             

            I have tested and work "better". The current source drops too but more slower.

            VLOW : Resistor divider to 2.9V

            VREF : 2.8V

            When Vdd(3.1V) drops below 2.7V I have an interruption.