- 18th March 2008, 18:21 #1
## Formula for calculating DAC output

Hi,

The logic levels used in a 6-bit R-2R 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

- 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, 05:29 #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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