adc, measuring digital output from analog input

spartekus · Dec 21, 2013

adc, measuring digital input(voltage and current) from digital output

Hi,

I need to measure analog input value of MCP3221, and show it on display. (with microcontroller)
but i dont know how i will know the analog input from its digital output.
maybe anyone has experience with it, page 13 of at datasheet should be related with this question.
thanks

rusty81 · Dec 21, 2013

It's very simple:

\[V_{in} = \frac{VDD}{4095}\cdot \,N \]

where N is the digital converted value (in base 10) that you get from MCP3221, VDD the operating voltage, 4095 come from \[2^{bit}-1 = 2^{12}-1 = 4095\]

Example, VDD=5V, N is, for that moment, 3045, which is the input voltage?

\[V_{in} = \frac{5}{4095}\cdot 3045 \approx 3.72\,V\]

So Vin can range only between 0V (0 digital) and VDD (4095 digital).

spartekus · Dec 21, 2013

thanks for your answer, in the begining, i thought for LSB, for binary). it is clear now.

adc, measuring digital output from analog input

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