EVAL-AD7476 Datasheet, PDF (8/12 Pages) Analog Devices – Evaluation Board for 1MSPS, 12-/ 10-Bit ADCs

EVAL-AD7476/77CB
DIGITAL STORAGE OSCILLOSCOPE.
When samples of data are captured, they are displayed on the
Digital Storage Oscilloscope. If the blackman-harris button
is turned on then the windowed data is also displayed on the
oscilloscope. The 'scope has been designed to act in a similar
way as a conventional oscilloscope. To the right of the
oscilloscope are several buttons that control the manner in
which data is displayed on the 'scope. The timebase for the
oscilloscope is automatically chosen by the software if the
Time/Div "Auto" button is on. The user can also select the
timebase by clicking in the Time/Div window and scrolling
up and down through the possible timebases. Similarly, the
vertical scale of the oscilloscope is chosen automatically if the
Volt/Div "Auto" button is on. The user also has the option
of selecting the desired vertical scale in a similar manner to
selecting the timebase.
The other buttons associated with the oscilloscope are:
grid
This button toggles the grid display of the oscil-
loscope on and off.
axis
This button toggles the axis display of the oscil-
loscope on and off
text
This button toggles the text displayed on the
oscilloscope screen on and off.
line
When the line button is on, the displayed samples
are joined together by lines. When this button is
off, the samples are displayed as points.
ac
When this button is on, the dc component of the
sampled signal is removed and the signal is
displayed. This has the effect of centering the
signal vertically on the oscilloscope screen. When
this button is off, the dc component is not
removed and the signal is displayed with its
horizontal axis corresponding to a code of 0. The
ac display option is useful for zooming in on a
low-level signal that has a large dc offset.
dual
When the "dual" button is on, the oscilloscope
screen is divided into two parts with the sampled
data display centered on one horizontal axis and
the windowed data display centered on another.
When the "dual" button is off, both traces are
centered on the same horizontal axis.
1
This button toggles the sampled data trace on and
off.
2
This button toggles the windowed data trace on
and off.
HISTOGRAM ANALYZER
The histogram analyzer counts the number of occurrences of
each code in the captured samples and displays a histogram
of these counts. The most frequently occurring code is
displayed in the center of the histogram. The analyzer is
normally used with a dc input signal and calculates the mean
and the standard deviation of the sampled data. The mean
and standard deviation are displayed in both volts and in units
of the lsb size of the converter. The histogram gives a good
indication of the dc noise performance of the ADC. The
standard deviation shows directly the noise introduced in the
conversion process.
Figure 5 Histogram Screen
–8–
REV. 0