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ADC conversion time doubts

Question asked by Deepak Kukreja on Jul 1, 2020
Latest reply on Jul 1, 2020 by Da Li

Hi,

 

I am using Kinetis K12 device MK12DN512VLK5.

I have few doubts regarding the ADC conversion time calculations given in the reference manual.

 

The reference manual provides the below formula for calculating the conversion time:

I understand that the above formula gives the total time for conversion and takes into account the

  • sampling time,
  • ADC conversion time as well as the
  • time required for averaging if that is selected.

Is my understanding correct?

 

 

My doubt arises because of the example time calculation shown in the reference manual:

My calculation for the above example (based on the formula given in the reference manual) comes to 1731.625 micro-seconds.

 

time = "3 ADCK cycles" + "5 bus clock cycles" + (32 x "34+20 ADCK cycles" )

ADCK clock cycle time is 1.000 uSec ( from ADCk freq. = 8 MHz/8 )

Bus  clock cycle time is 0.125 uSec ( from 8 Mhz bus clock frequency)

 

I am misunderstanding something or is this an issue in the reference manual?

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