How to estimate the total ADC conversion time?

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a_ziliu
Posts: 207
Joined: 20 Mar 2017, 10:52

31 May 2021, 16:20

The total ADC conversion time follows the equation below:
TADC = TSMP + Tconv
Where
TADC = total conversion time
TSMP = sampling time
Tconv = conversion time = 1.625us

The sampling time follows the equation below:
TSMP = where
With the condition Fsys = 16MHz, TSMP(min) = = 0.375us

The ADC controller supports continuous conversion mode and interrupt conversion mode, and the specific calculation formula is detailed below.
Continuous conversion mode
The total ADC conversion time is
TADC(min) = TSAMP(min) + TCONV = 0.375us + 1.625us = 2us

then the ADC conversion rate is
FADC = = 500 kHz
Thus, the ADC conversion rate is 500 kHz.

Interrupt conversion mode
Setting ADC converting software start trigger bit and waiting for ADC flag to be set requires about 9 cycles, as shown in the figure below.


The total ADC conversion time is
TADC(min) = TSMP(min) + TCONV + Tinstruction cycle
= 0.375us + 1.625us + 9*us = 2.5625us
then the ADC conversion rate is
FADC = = 390 kHz
Thus, the ADC conversion rate is 390 kHz.

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