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AMC1200: Calculation of voltage filter pole when AMC1200 is used

Mark Feller
Intellectual 890 points
Part Number: AMC1200

When looking on the MCU side of sample code for motor control, the voltage filter pole is needed on the sensing side, but the reference circuits are simple voltage dividers.

I'm working with a platform that uses the AMC1200 for voltage sense.  

Can you provide guidance on how I should compute the voltage filter pole with the AMC1200 included?

Thanks!

  • 0
    TI__Mastermind 48791 points

    Hi Mark,

    Is there a design of some sort you are referencing? 

    AMC1200 is often connected to a voltage divider for voltage measurement. 

  • 0 in reply to Alexander Smith
    Intellectual 890 points

    Hi Alex,

    The MCU side / sample code uses just a voltage divider with capacitor as filter.  spruhj1i.pdf, page 243 as an example.

    The AMC1200-based design does have the voltage divider on the input, but no capacitor.  I was wondering if some filtering is done internal to the AMC1200, or is the lack of capacitor either a "don't care" or a "miss" on the AMC1200-based design.

    Thanks!

  • 0 in reply to Mark Feller
    TI__Mastermind 48791 points

    Hi Mark,

    Thank you for providing this detail - I am not familiar with this document as I support the AMC1200 itself. We recommend an RC filter with differential input capacitor to act as a charge bucket - as the input structure of the AMC1200 is similar to a SAR ADC. For voltage sensing, if the frequency of the signal is low than perhaps this is not necessary.