When my DAC output is from 0-1V, and is fed into 10-bit AD9218 which is set to binary mode, what binary value will I get when the input is -10mV?
- posted
18 years ago
When my DAC output is from 0-1V, and is fed into 10-bit AD9218 which is set to binary mode, what binary value will I get when the input is -10mV?
I assume you mean -10mV AC coupled into the AD9218 (it is internally biased at 1/3Vdd)
You would have 1/200 of the negative dynamic range, or 1/100 of the span range which gives -10/1024.
As the output is set for 2s complement, the output will run from +511 to -512 (Hex = 0x1FF at +511 to 0x200 at -512) for an input of 1Vp-p, so in this case, you should get 3F6, rounded to the nearest integer. (-10 decimal)
Cheers
PeteS
further to my other reply, if you are using offset binary, then you will get N[off] - 10 (decimal). The output of the DAC at Vin(centre) should be 0x200, so you would get 1F6.
Cheers
PeteS
On 28 Nov 2005, Frank put down his happy meal and blurted:
I'm lovin' it.
Thank you Peter.
My digital output is from 0-1024 (1MHz sine wave 0 -> -1, 1024 -> +1) and fed into the
10 MSBs of DAC (TI DAC290x-EVM). Due to noise, the DAC has some below zero values on oscilloscope (-20mV ~ 0.8V). When I connected this signal to ADC, how do I ensure that the digital output is the same (or nearly the same) value of my original digital input? (The requirement is such that after I captured the ADC O/P with logic analyzer, plotted in graph of 0~1024, it shows a sine wave without bad codes).
I am so hard doing this assignment for the year end bonus's sake. After the money enters my purse, I can BURP about all the nice food in the entire city.
I'm lovin' it. Kekekeke...................
If your DAC is really set to produce outputs from 0-1V, any apparent negative voltages are necessarily analog noise. This isn't a question about bit values.
There are straight binary, offset binary, and two's-complement binary. If you want details, point me to relevant data sheets.
Jerry
-- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.