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CT Sensor signal conditioning ?

Riko Husin
Intellectual 510 points
Other Parts Discussed in Thread: INA190

Dear TI Members,

I want to use this CT transformer as my current sensor,

https://au.rs-online.com/web/p/current-transformers/1243893/    

What circuit will you recommend for it before feeding to ADC ?

Kind regards and thanks

  • 0
    TI__Mastermind 26335 points
    Hello Riko,

    Thank you for using our forum. I presume you are using the CT to take a large current from your primary load and transform it to a smaller load seen on your secondary, the CT. From here you are looking for a circuit that can measure this load and provide an analog output to a downstream ADC. I think a current shunt monitor will meet your needs. What is your max primary or secondary current? This will determine the size of your shunt. I presume your ADC max input is 5V, if so the shunt will be ~Device Supply/Gain/Imax. What is your minimum current resolution? All current shunt monitors will not have a zero volt output for zero load condition. There will always be some voltage offset that produces error at lower current levels. If your minimum resolution is in the low mili-amp range, most of our devices will work for you. However, if your minimum is in the low micro-amp range you may need to consider our INA190.
  • 0 in reply to Patrick Simmons
    Intellectual 510 points

    Yes, I want to sense 50A AC and monitor it with ADC with maximum input 3.3V.

    Any suggestions for which CT I can use with INA190 ?

    Do you have an evaluation board for INA190 ?

    Thanks

  • 0 in reply to Riko Husin
    TI__Mastermind 26335 points

    Hello Riko,

    I do not have a CT to recommend for you.  However, assuming you are measuring a 50A pk pk swing with a 0.002ohm shunt and no CT you could directly measure as low as 75mA ~10% max error, 750mA  ~1% max error across your measurement range.

    The EVM can be found here.