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generators can not provide a level of distortion low enough to
evaluate high resolution ADCs.
4.1 Software Installation
The WaveVision software provided requires 300k bytes of
hard drive space and will run under Windows 3.1 or later.
1.
Insert the disk into a 3.5" floppy drive.
2.
Copy the program ADC16061.EXE to the desired
subdirectory on you computer's hard disk and
4.2 Setting up the ADC14071 Evaluation Board
This evaluation package was designed to be easy and simple
to use, and to provide a quick and simple way to evaluate the
ADC14071. The procedures given here will help you to
properly set up the board.
4.2.1 Board Set-up
Refer to Figure 1 for locations of connectors, test points and
jumpers on the board.
1.
Set jumpers to their default position, or as desired.
Table 1 explains the function of the jumpers. Jumpers
JP1, JP2 and JP3 should all be moved together. That is
all of these should be either in their default positions or
all not in their default positions.
2.
Connect power to the board per requirements of
paragraph 3.7.
3.
Connect a cable with DB-25 connector between board
connector P1 and a parallel port on your computer.
4.
Be sure a 14MHz (14.31818MHz is fine) clock oscillator
(Y1) is in place, or connect an external clock source to
BNC J2, at the lower right corner of the board.
5.
Be sure jumper JP4 is set to select the clock source
used. The default position selects the on-board
oscillator, Y1.
6.
If using an external clock source, place a shorting bar
across the pins of JP5 to terminate the clock input, if
needed and connect a clock source to BNC J2.
7.
Connect an appropriate signal source to J1.
8.
Turn on the power and press reset button (S1). Confirm
that Red LED D5 is on, indicating the clock presence.
4.2.2 Quick Check of Analog Functions
Refer to Figure 1 for locations of connectors, test points and
jumpers on the board. If at any time the expected response is
not obtained, see section 4.2.6 on Troubleshooting.
1.
Perform steps 1 through 8 of Section 4.2.1. Adjust the
input signal at J1 for 1V P-P .
2.
JP4 - Short left two pins to select the on-board clock
oscillator (Default position).
3.
JP1 - Short upper two pins of JP1 and the right two pins
of JP2 and JP3 to use the op-amp circuitry (Default
positions).
4.
Turn on the power to the board.
5.
Adjust VR2 for a voltage of 2.0V at TP1.
6.
Scope TP4 to confirm the presence of an ADC clock.
7.
Scope the signals at TP12 and TP13 to be sure they
are present at a 2V P-P level.
8.
JP1 - Remove the short on the upper two pins of JP1
and the right two pins of JP2 and JP3. Short lower two
pins of JP1 and the left two pins of JP2 and JP3 to use
the to use the transformer T1.
9.
Adjust the signal source at Analog Input J1 for a signal
amplitude of approximately 2V P-P , centered at ground.
10.
Scope the signals at TP12 and TP13 to be sure they
are present at a 2V P-P level between ground and +2V.
11.
Short right two pins of JP4 to select an external clock
source. Connect a clock source to BNC J2.
12.
Scope TP4 to confirm the presence of an ADC clock.
This completes the testing of the analog portion of the
it.
RUN
evaluation board.
4.2.3 Quick Check of Software and Computer Interface
Operation
1.
Perform steps 1 through 5 of Paragraph 4.2.2, above.
2.
Turn on the power to the board and press reset button
(S1).
3.
Supply a 1Vp-p sine wave of about 1MHz at Analog
Input BNC J1 and adjust it so that yellow and green
LEDs D3 and D4 are not on.
4.
If only one of these LEDs is on, adjust VR2 until they
are both off or both on, then go back to step 3.
5.
Be sure there is an interconnecting cable between the
board and your computer parallel port.
6.
Run program ADC16061.EXE.
7.
Acquire data by clicking on the ACQUIRE icon or by
pressing
ALT
calculations can take a few seconds.
8.
When transfer is complete, the data window should
show many sine waves. The display may show a nearly
solid area of red, which is O.K.
Figure 2. The WaveVision captured display of a 1MHz sine wave
at 7MSPS. The input signal should be filtered to remove
harmonic distortion and should be stable to prevent averaging of
the data in the FFT process.
9.
Note the max and min codes at the upper right of the
data window. These should be within the limits of
±8190. If the signal is outside of these limits, the signal
may be clipped (and distorted). If this is the case, lower
the input level to the board and go back to step 7.
10.
With the mouse, you may clilck and drag to select a
small portion of the displayed waveform for better
examination.
11.
Click on the FFT icon or type
The FFT data will provide a measurement of SINAD, SNR,
THD and SFDR (See Figure 3 ), easing the performance
verification of the ADC14071.
7
, P, X or
-X. Data transfer and
CTRL
, P, F or
ALT
CTRL
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-F.
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