Analog Devices AD7400A Evaluation Board EVAL-AD7400AEDZ EVAL-AD7400AEDZ Datenbogen

 

Rev. 0 | Page 9 of 16 

On the Data Capture tab, you can select the number of samples 
to be captured from the drop-down menu. The default number 
of samples is 8192; you are free to change this as required. The 
desired display option is selected by clicking the Waveform, 
Histogram

, and FFT tab. 

The Waveform tab displays a digital storage oscilloscope  
(DSO) that allows you to display a waveform. When samples  
are uploaded from the EVAL-CED1Z, they are displayed here. 
The samples are displayed as integer code values. 

At the bottom left of the graph are the zoom options. These 
allow you to zoom in and out to get a closer look at a sample,  
if required. The Waveform Analysis section, located beneath 
the waveform graph, contains information about the samples 
taken, for example, minimum/maximum position or velocity, 
the spread, the standard deviation, and the mean. 

The Histogram tab displays a histogram of the captured ADC 
codes. It can be used to give an indication of the performance  
of the ADC in response to dc inputs. The Histogram Analysis 
section contains information about the samples taken, for 
example maximum and minimum codes captured. 

The FFT tab displays a fast Fourier transform (FFT) plot. The 
FFT is typically used for examining the performance of the ADC  
in the frequency domain. The Spectrum Analysis section 
contains information about the samples taken, for example,  
ac specifications.  

On the Linearity tab, you can select the number of hits per  
code to be captured for the linearity analysis. The desired 
display option is selected by clicking the Histogram, INL,  
DNL

, or Summary tab buttons. To initiate the data collection, 

select the Get Linearity Data button. The data collection and 
analysis takes a few seconds to complete. The greater the number 
of hits per code selected the longer the analysis takes. 

 

The Histogram tab displays a histogram of the captured ADC 
codes. It can be used to give an indication of the performance  
of the ADC in response to dc inputs. The Histogram Analysis 
section contains information about the samples taken, for 
example maximum and minimum codes captured. 

The INL tab displays an INL plot for the 

 or 

This plot can be used to examine the dc performance of the 
ADC. The Linearity Analysis section contains information on 
the maximum and minimum INL error and the code at which 
this error occurred. It also shows the total number of hits per 
code and the number of samples taken.  

The DNL tab displays a DNL plot for the AD7400A or AD7401A. 
This plot can be used to examine the dc performance of the 
ADC in conjunction with the INL plot. The Linearity Analysis 
section contains information on the maximum and minimum 
DNL error and the code at which this error occurred. 

To initiate a conversion and capture the sample data, click the 
Sample

 button or the Continuous button. Both the Sample  

and the Continuous buttons are located on the top right hand 
corner of the Data Capture tab. When you click the Sample 
button, the software instructs the EVAL-CED1Z to take the 
required number of samples at the required frequency from  
the evaluation board. The EVAL-AD7400A/AD7401A runs 
with sampling speeds less than or equal to 39 kSPS. This sampling 
rate can be altered by changing the decimation rate selected for 
the filter. You can choose the decimation rate and the number 
of samples to be taken.  

The samples taken are then uploaded and displayed. An FFT 
and/or histogram can be calculated and displayed. If you click 
the Continuous button, the software repeats the process indefi-
nitely until you click Stop. (The Continuous button switches to 
Stop

 when selected).