Analyzing op-amp circuit - Please Help

Discussion in 'Homework Help' started by cass1111, Nov 18, 2012.

  1. cass1111

    Thread Starter New Member

    Nov 18, 2012
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    Hello, I am new to this forum, this is my first post. I need to analyze this circuit and explain/understand what the function of each component is. Can someone please breakdown this circuit to help me better understand it? Help would be greatly appreciated.

    * Please click on the attached thumbnail to see the circuit - sorry, I'm still learning how to attach the files so that they post correctly!! *

    This is what I have so far...

    C1003 - ESD cap
    C1011 - bypass cap
    IC1000 - op-amp
    R1047 - current limiting resistor
    R1047 + C1027 - low pass filter

    As you can see, I need a lot of help still! And if you could explain it in layman's terms, that would be a huge help!

    Thank you again for your time and help!
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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  3. cass1111

    Thread Starter New Member

    Nov 18, 2012
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    Jony130... Thank you so much for taking the time to reply and for the direction you have me! I have stepped away from engineering for a few years, so I am trying to shake some rust off in my circuit analysis!

    Looking up he Sallen-key low pass filter topology, I figured out how to calculate the resonant frequency and the Q factor. I was wondering though, if this opamp topology is already serving as a low pass filter, what would be the purpose of having R1047 and C1027 also configured as a low pass filter? ... Or is that not their purpose?

    Finally, is R1047 also being used as a current limiter? And if so, how would i calculate what the worst case current would be seen going through R1047?

    Thanks again to you and anyone else who takes the time to point me in the right direction!
     
  4. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    I don't know why they use this RC passive filter. Maybe they need third order filter instead of second order filter.
    TLC2272 don't have any short circuit protection. And also TLC don't like "heavy" loads.
    As for selection such a short circuit protection resistor see data sheet figure 18 and 20 on page 35 and use Ohms law.
     
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