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18th March 2008, 18:21 #1
Formula for calculating DAC output
Hi,
The logic levels used in a 6bit R2R ladder DAC are 0=0v and 1=+5v.What is the binary input when the analog output is 4V?
Thanks in advance...

18th March 2008, 18:21

18th March 2008, 19:02 #2
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Re: DAC
Hi,
(4÷5)64 in binary.
Regards,
Laktronics

18th March 2008, 19:02

19th March 2008, 22:41 #3
Re: DAC
i think major are saying right

19th March 2008, 22:41

20th March 2008, 03:48 #4
Re: DAC
hi laktronics,
Can u say me is this standard formulae of just...?
Thanks

20th March 2008, 05:24 #5
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Re: DAC
Hi friends,
The standard formula for calculating the DAC output is, for example of 6 bit DAC
Output of DAC in Volts =
((32*D5 + 16*D4 + 8* D3 + 4*D2 + 2*D1 + 1*D0)*SUPPLY VOLTAGE)/(2 POWER 6)
Thats all.
All the best,
N.Muralidhara
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20th March 2008, 05:24

20th March 2008, 05:29 #6
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Re: DAC
Originally Posted by graciousparul
hello laktronics you also check it and please let me kno is it true or false..??
Thanks you..
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20th March 2008, 18:15 #7
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Re: DAC
Hi H_D_R,
The equation given by you is same as that given by Mr Murali as shown below:
Vo = KRf ( A1/2 +......+ A8/256) (a) ; where A1..A8 is a binary number
From the above equation,
Vref = KRf (1) (b) ; (A1/2+... +A8/256) =1 since for Vref A1 to A8 all are one.
Dividing (a) by (b),
Vo/Vref = (A1/2 +.....+A8/256)
Multiplying both sides by 256,
(Vo/Vref) 256 = (128.A1+64.A2 +......+ A8 ) ....(c) which is same as Mr.Murali's
eqtn. applied to a 6bit DAC.
The above eqation (c) will be valid for unipolar DACs.For bipolar offset binay DACs also it will hold good if you take Vref as total span of Vref to +Vref.
The equation also applies to similar ADCs if you replace Vo by Vin.
Then there are sign magnitude and 2's complement codes for which +ve and ve outputs are coded separately.
Regards,
Laktronics

21st March 2008, 06:47 #8
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Re: DAC
yes, i knew that laterly...
bt i think this will make more clear to my friend "graciousparul".
thats it...
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