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ADC Requirements for XC164CS

Vivek Tailor

Hi everyone,

I am designing DC/DC converter for high frequency applications. I am using current close loop control to control the converter. Now, the Xc164Cs has in built ADC. I need to check the output voltage and the current as well as input voltage and the current of the converter. I just want to know "how quickly i need to measure the inputs?" and how can i check that?

Cheers

vivek

Parents
  • 0 in reply to Vivek Tailor

    The information you are seeking can be found in the data sheet and users manual.

    For an analog to digital conversion the fastest you can perform a conversion is from the following formulas:

    conversion time (10-bit) = 40 * tBC + tS + 6 * tSYS
    conversion time (8-bit) = 32 * tBC + tS + 6 * tSYS

    Conditions...
    1) The maximum frequency of the ADC Base Clock is 20MHz.
    2) The maximum SYStem clock is 40MHz
    3) The minimum Simple Time = tBC * 4 * (<ADSTC> + 1)
    4) Post calibration is off

    Assumptions: fSYS = 40 MHz (i.e. tSYS = 25 ns), ADCTC = '01', ADSTC = '00'
    Basic clock fBC = fSYS / 2 = 20 MHz, i.e. tBC = 50 ns
    Sample time tS = tBC * 8 = 400 ns

    Conversion 10-bit:
    With post-calibr. = 52*tBC + tS + 6*tSYS = (2600 + 400 + 150) ns = 3.15 us
    Post-calibr. off = 40*tBC + tS + 6*tSYS = (2000 + 400 + 150) ns = 2.55 us

    Conversion 8-bit:
    With post-calibr. = 44*tBC + tS + 6*tSYS = (2200 + 400 + 150) ns = 2.75 us
    Post-calibr. off = 32*tBC + tS + 6*tSYS = (1600 + 400 + 150) ns = 2.15 us

Reply
  • 0 in reply to Vivek Tailor

    The information you are seeking can be found in the data sheet and users manual.

    For an analog to digital conversion the fastest you can perform a conversion is from the following formulas:

    conversion time (10-bit) = 40 * tBC + tS + 6 * tSYS
    conversion time (8-bit) = 32 * tBC + tS + 6 * tSYS

    Conditions...
    1) The maximum frequency of the ADC Base Clock is 20MHz.
    2) The maximum SYStem clock is 40MHz
    3) The minimum Simple Time = tBC * 4 * (<ADSTC> + 1)
    4) Post calibration is off

    Assumptions: fSYS = 40 MHz (i.e. tSYS = 25 ns), ADCTC = '01', ADSTC = '00'
    Basic clock fBC = fSYS / 2 = 20 MHz, i.e. tBC = 50 ns
    Sample time tS = tBC * 8 = 400 ns

    Conversion 10-bit:
    With post-calibr. = 52*tBC + tS + 6*tSYS = (2600 + 400 + 150) ns = 3.15 us
    Post-calibr. off = 40*tBC + tS + 6*tSYS = (2000 + 400 + 150) ns = 2.55 us

    Conversion 8-bit:
    With post-calibr. = 44*tBC + tS + 6*tSYS = (2200 + 400 + 150) ns = 2.75 us
    Post-calibr. off = 32*tBC + tS + 6*tSYS = (1600 + 400 + 150) ns = 2.15 us

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