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AMC1304 Filtering

Robert Adsett
Guru 27665 points
Other Parts Discussed in Thread: AMC1100, AMC1200, AMC1304M05, AMC1304M25, TMS320F28377D

I just recieved some preliminary information on the AMC1304.  It looks like an interesting possibility for some of our uses.

I didn't immediately notice that it sends out a delta-sigma bitstream and that does present a bit of a problem.

The solution in the eval board is too expensive for our needs.  We would need to be able to condition this locally and then send it via CAN and maybe as an analog signal as well. We use a TIVA processor for our peripheral measurements now and moving to something other than an ARM core would be a considerable barrier.

Any suggestions for filtering the output?  Preferably with something like an SPI interface although converting back to analog might work as a fallback. 

 

Robert

  • 0
    TI__Genius 9975 points

    Hello Robert,

    What is the bandwidth of the analog signal you are interested in acquiring and what resolution/accuracy level are you interested in? Depending on these parameters and the isolation level required you may want to also look into the AMC1200 and AMC1100. They are isolated amplifiers (analog input - analog output).

    Best regards,

    Jose

  • 0 in reply to Jose Duenas
    Guru 27665 points

    Bandwidth is reasonable, not more than 10kHz probably only a few kHz is needed.

    We have a slower measurement where the needed bandwidth can be measured in 10's of Hz.

     

    Isolation required will be around 1500V DC. 

    Robert

  • 0 in reply to Robert Adsett
    Guru 27665 points

    Oh, and accuracy of around 0.1% would be my target.  Resolution matters only to the extent it's needed to provide the accuracy.

     

    Robert

  • 0 in reply to Robert Adsett
    TI__Genius 9975 points

    Hello Robert,

    The AMC1304M25 has a full scale range of 500 mVpp and the AMC1304M05 has a full scale range of 100 mVpp. For these ranges, un-calibrated accuracy of 0.3 %FSR can be achieved.

     At room temperature, calibrated accuracy of 0.006 %FSR can be achieved with these devices when paired with a Sinc 3 filter running at 20 MHz (such as that included in the TMS320F28377D microcontrollers). With this type of filter, the -3 dB frequency of the digital output signal is 20.4 kHz at a sampling rate of 78.12 kSPS and 13.8 ENOB.

    The working insulation voltage of 1500 VDC is for the lifetime of the part (typically 25 years).

    Hope this answers some of your questions.

    Best,

    Jose

  • 0 in reply to Jose Duenas
    Guru 27665 points

    Thanks Jose, that does help.

    Robert