AD7193 Accuracy Issues...

   Hello,

AD7193 calibration issue is solved & now i am getting values of offset register & Full scale register as follows.

      Offset register=8389236

      Full scale register=5584950

  AD7193 Configured as follows:

Mode register=0x0C0060

Configuration register=0x040118

Gain=1, Vref1=2.5, Chop disable, FS[9:0]=96,Continuous conversion mode,unipolar configuration

0 to 2.5V dc input connected to ch1 to check linearity of  ADC.

But i am getting 3.5% error (of the reading) near 0.1V

Zero: 0v , ADC counts=0

Span: 2.5V, ADC counts = 16754713

i/p                   ADC counts          Calculated Counts        Error(%)

0.10001          644500                     670228                     3.8387

0.20001         1315798                   1340390                    1.8346

0.30001         1987091                    2010551                   1.1668

0.4001            2660577                   2681316                   0.7734 

0.5001            3331311                   3351478                   0.6017

0.6001            4002490                   4021639                   0.4761

.......

.......

2.0001            13398607                  13403902                0.0394

2.2001            14741788                  14744225                0.0165

2.4001            16083274                  16084548                0.0079

2.5001            16754713                  16754713                

 

 

Please help me how to minimize Error..

Expected error for my application should be <.25% of the reading near zero.

 

Any help will greatly appreciated...

  • hello mam,

    Did you mean to say that i should connect AINCOM pin to 1.25V(if no kindly suggest the workaround)(i kept provision in my circuit to connect it to 1.25V )  & check for linearity from 0.25V to 2.5V.

  • hello..

    I will try & get back to you soon...

    Thanks

  • Hello mam,

    I am checking for linearity of AD7193 with variable input of 0-2.5V for performance analysis since I have not used it before anywhere…

    My Actual application is different.

    In my Actual operation I want to measure differential signal of peak to peak 0- 15mV  (5.73Hz) with gain of 128 which is override on 1.25V dc level & connected to AIN7 & AIN8 of AD7193.… so headroom meets automatically with buffer enable mode also..In this case where should I connect AINCOM??...Also for this application I need samples from known point so how I should implement SYNC pin function??... To use SYNC pin as start of conversion signal I need to give low to high transition on SYNC pin to do this is it necessary to synchronize SYNC pin of AD7193 with SCLK of AD7193????... If YES then rising edge of SYNC pin synchronize with which edge of clock????.... If I use SYNC pin as Start of conversion then is it necessary to put AD7193 in single conversion mode & read data with command 0x58???...

  • Hi...

    Thanks a lot mam...

    Glad to inform you that accuracy issue is solved... Accuracy is too good..see the results...

    Thanks

    latika

  • Hi..

    Now i will try with the differential mode & get back to you soon..