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single supply op-amp

VIJITH C V
Prodigy 40 points
Other Parts Discussed in Thread: OPA313, TINA-TI

Hi all,

             Can anybody help me with a single supply op-amp circuit,whose input is dealing with 230 v supply and the o/p is controlled by the gain resistors....i need to convert  230 v into 1.25 v range.

  • 0
    TI__Guru* 93105 points

    Hello Vijith,

    I assume that the 230 V is the RMS value of an ac line source which would be 848.4 V peak-to-peak, or 424. Vpk, And the output range from the circuit is to be 1.25 V peak-to-peak. That output voltage would have to be centered about a dc level since yo specified single supply.

    I think a simple op amp buffer using a single-supply op amp such as the OPA313 should work. I show a circuit below where the output dc level, 1.5 V, is established by a simple resistive voltage divider connected between the 3 V supply and the non-inverting input. Then, a capacitive divider precedes the non-inverting input.. The way I have it set up the C1 to C2 Xc ratio needs to be about 678:1. I added C3 across C1 to set the divider for a 1.25 V range.

    You can play with this circuit a bit and get things adjusted as you need. I've included the TINA simulation file that I used.

    Regards, Thomas

    PA - Linear Applications Engineering

    OPA313 Cap Divider_01.TSC

  • 0 in reply to Thomas Kuehl
    Prodigy 40 points

    Thank u Mr Thomas Kuehl .Of course it will be useful for me, but I am not able to access single supply op-amp in TinaT..can u help me with that .How do I include OPA313 in library ?

  • 0 in reply to VIJITH C V
    TI__Guru* 93105 points

    Hello Vijith,

    You should be able to store the TINA file I sent you, OPA313 Cap Divider_01.TSC, and then open it from TIINA-TI. Once the OPA313 model shows in the circuit you can copy and paste it into your own schematic.

    I checked the model library updates and it looks like TINA-TI's doesn't include the OPA313. In fact, it is missing a lot of our newer models. I will check with the group that maintains the models and ask if they can do an update. Once they are in place then there is a way to update the library from within TINA.

    Regards, Thomas

    PA - Linear Applications Engineering