Current Shunt Amplifier!

Discussion in 'The Projects Forum' started by rigers, Mar 8, 2012.

  1. rigers

    Thread Starter New Member

    Jun 14, 2011
    20
    0
    Hello,

    I wanted to use a current shunt amplifier to measure the current through a circuit. I was thinking of getting the INA212 from TI because it has a Gain of 1000. The reason for this gain is because I want to be able to go down to nano-amps. I wanted to know what's the minimum voltage that the device can measure between the two pins because I want to get a Rs as small as possible. I want to be able to set a constant current or voltage so there is a feedback. Should I put the current sense on high side or low side? Suggestions?
    Here's the link for the component.

    http://www.ti.com/product/ina212

    Thank you!
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    The its the resolution of the ADC that will determine your measurement resolution not the gain of the op amp. For example an 8 bit ADC can only have 256 (2^8) levels of measurement. While a 10 bit will give you 1024 levels.
    You choose the gain based on the full scale voltage range of the ADC.
     
  3. rigers

    Thread Starter New Member

    Jun 14, 2011
    20
    0
    I'm using a 12 bit ADC and will go to 16 bit later which gives me 76uV per bit(based on a 5 volt scale). I know the issues about the resolution and I have considered them. My question was would the device or any regular instrumentation amp be sensitive enough to pick those minute voltage changes which in this case would be 76uV/1000=76nV, which would be the voltage drop across the shunt. I might use one with 10000 gain to go even lower.
     
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