Download EXPERIMENT: D/A Converter

EGR 240 Lab 2. May 8-9, 2006.
Rev. A
EXPERIMENT: D/A Converter – PSpice and Soldering
References
1.
Lecture slides D2.2: Digital to Analog (D/A) Converter and D3.2: Analog to Digital (A/D)
Converter.
2.
Kerns and Irwin textbook: Section 8-6, 8.6.1 on pages 311 – 314,.
3.
PSpice Tutorial (.pdf file available on class website)
LAB
Part A. PSpice.
1. Simulate the 2R-R resistor network shown in Fig. 1 using PSpice by following the PSpice
Tutorial that you can download from the class website. Print out your PSPice circuit diagram
and the simulated waveform.
2K
V
B3
1K
2K
B2
1K
2K
B1
1K
2K
B0
2K
Figure 1
Have your lab instructor sign your results.
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Part B. Soldering.
1. Solder the circuit shown in Figure 2 on your circuit board.
+5V
Vin
2
3
2.0 K
B3
Upper-left
Corner
1.0 K
2.0 K
B2
(RED)
(YELLOW)
1.0 K
LM311
2.0 K
B1
(9" Wires)
1.0 K
(BLACK)
(WHITE)
(3" Wires)
Vin
2.0 K
B0
(RED)
(RED)
+5V
(YELLOW)
2.0 K
+5V
GND
1KΏ
(BLACK)
gt
(WHITE)
(BLACK)
(From existing
circuit)
Figure 2
Have your lab instructor check your results.
2
1.0 K
8 5
6
4 1
7
gt
Part C. Circuit Test.
1. Connect the output, gt, of your D/A converter to the left-most green LED on the PLDT-3
board. Connect B3, B2, B1, and B0 to the four right-most toggle switches on the PLDT-3
board. Connect Vin to a variable power supply (0 – 5V) with the voltage set initially to zero.
2. Turn all toggle switches off. Set Vin to some voltage between 0 and 5 volts. Measure this
voltage with the multimeter and record the voltage, Vin, in Table 1. While maintaining this
voltage, turn on the toggle switch B3. If the green LED is lit, leave it on; otherwise, turn it
off. Repeat this procedure for B2, B1, and B0. The resulting switch setting will be the 4-bit
binary number representing the analog voltage, Vin.
3. Measure five different voltages using this method and record your results in Table 1.
Analog voltage, Vin
Table 1
4-bit Binary value
Hex value
Have your lab instructor sign your results.
Answer questions 5 – 8 on the class website for next week:
5. List the steps that you followed in simulating the circuit in Figure 1 using PSpice and
describe how you can install a version of PSpice on your own computer.
6. Derive the equation for V in Fig. 1 in terms of B3, B2, B1, and B0.
7. Explain why the procedure you followed in Part C gives a hex value proportional to the
voltage applied at Vin.
8. Explain how the procedure you followed in Part C implements the successive approximation
method of implementing an A/D converter.
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