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Voltage Limiting Circuit for Codec

Discussion in 'Electronic Design' started by Barry, Jan 31, 2004.

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  1. Barry

    Barry Guest

    Hallo again all,

    You might not remember, but a few months back you guys helped me
    design a photoreceiver, as outlined here -

    I've been using this circuit ever since with no problem to report -
    thanks again. I'm now at the stage though where I need to connect this
    circuit to the Codec on my DSP board. The codec specs are here, (the
    evm is an evaluation module for the aic23 chip which I'm using as a
    daughterboard for my dsp motherboard) -

    In order to protect my Codec, I've come up with the following limiter
    circuit (as an adition to my origional receiver) -

    This circuit limits the output voltage to between 1.5 and -1.5V.
    Ignore the LM324 - its readily available in PSpice, but I would use
    the LF353 instead. The codec line input takes 1 Volt RMS. In my
    limiter circuit, the current source again represents my photdiode.
    I've excluded the rest of the origional reciever circuit, such as the
    2222 in order to simply things.

    Is this a reasonable design?

    What value of resistor should I place between the op-amp's output and
    the codec's input?


  2. Barry

    Barry Guest

    Any suggestions?
  3. Barry

    Barry Guest

    My server is going down alot of late - MyDoom related perhaps. I've
    therefore copied my stuff to a geocities page also -

    under the heading - "Limiter Design" on that page.

    The final circuit I've presented on that page is the circuit I'm
    planning to interface to my codec. First of all, have I designed this
    final circuit correctly? Sould I connect the opamp output directly to
    the ADC, or should there be a resistor between them? What would its
    value be? And should I include a cap also to high-pass filter any high
    frequency noise?

    Thanks for your help,

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