# Calculating resolution.

Discussion in 'Electronics Homework Help' started by Mymla, Nov 9, 2016.

1. ### Mymla

37
3
May 4, 2015
Hey everyone,
could anyone point me in the right direction to working out this question. I have the answer but not sure how to work it out of the question.

Calculate the resolution the following convert given that Vref=5V.

8 Bit

Is this a correct formula to use? (Vin/Vref) * 2^bitdepth

5,165
1,087
Dec 18, 2013
Hello. How I do it is this 5/((2^8)-1) and that gets me pretty much the same answer as you. Thanks

3. ### Mymla

37
3
May 4, 2015
Thankyou! 5,165
1,087
Dec 18, 2013
No probs.

5. ### AnalogKid

2,482
715
Jun 10, 2015
Divide, not multiply.

ak

6. ### dorke

2,342
665
Jun 20, 2015
You shouldn't subtract 1.
To convince yourself check the case of 1 bit 7. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,482
2,830
Jan 21, 2010
Oddly enough that was the same argument I used to convince myself that you must subtract 1.

8. ### dorke

2,342
665
Jun 20, 2015
I can understand why.

For 1 bit we have 2 states "0" and "1".
How do we decide which state are we in?
"0" if we are below 1/2
"1" if we are above 1/2

What is the resolution than?
I would say 1/2 not 1...  5,165
1,087
Dec 18, 2013
Um I used to do it the other way and then I read on some website a time a go you should subtract 1. I am not saying your wrong...let me see if I can find the website.
Cheers

5,165
1,087
Dec 18, 2013
Not the website I saw but he mentions -1. But I think where I might be wrong is the maximum value FSD is Vref -1bit of resolution? Is that correct?

11. ### dorke

2,342
665
Jun 20, 2015
Actually you are correct my bad.

The definition of resolution is "the value that 1LSB equals to".
In the case of 1bit it is indeed 1.
so ,subtraction of 1 is the correct way to calculate the resolution.

Another value is the "error" of a converter this is 1/2 LSB
no -1 here.

5,165
1,087
Dec 18, 2013
Phew, thought I was going mad Cheers  