Download Lab #2: TTL and CMOS Specifications

Lab #2: TTL and CMOS Specifications
SAIT- ENT-DIGI-260
Lab #2: TTL and CMOS Specifications
Updated January 2010
Print pages 4 and 5
Objectives:
1. Plot transfer characteristic curves for TTL NAND (7400) and CMOS NAND
(4011) gates.
2. Determine the power supply and logic input current requirements of logic
devices.
3. Compare measured values with those in the specification sheets.
Pre-Lab Preparation:
1. Attend lectures and review the theory of electrical properties of gates and
devices.
2. Read the textbook chapters, manufacturer specification sheets and on-line
materials that relate to the TTL and CMOS logic families.
Equipment Required:
1.
2.
3.
4.
5.
6.
7.
Experimenter’s board with 5V power supply
Function Generator
Oscilloscope
DC meter
PC, with Excel,
Access to specification sheets
Parts kit
Additional Notes:
1. Remember to offset the function generator. Marks will be deducted.
2. Remember how to properly use an ammeter.
3. Do not make measurements while using the probe or an output LED, as
these will have a loading effect on your circuit and skew the
measurements.
4. Circuit simulations are not required for this lab.
5. Graphs must be neat and labeled appropriately. You may use Excel to
create the graphs.
6. This is a 2-person group lab.
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Lab #2: TTL and CMOS Specifications
SAIT- ENT-DIGI-260
Procedure 1:
Transfer Characteristics Curves
1.
Using a 7400 and/or 74LS00 IC, create a transfer characteristics curve
by doing the following:
a. See the manufacturer specification sheets for a sample of the
transfer characteristics curve.
b. Connect one input of the NAND gate to Vcc, making the NAND
gate an inverter. Use a 1kΩ pot as a voltage divider across Vcc
and ground to provide a variable input voltage to the gate. See
Figure 1 below.
c. Measure a number of values of VIN and VOUT using DC meters. See
figure #1. Note: Due to Vt+ and Vt- (hysteresis), turn the potentiometer in the
same direction for accurate measurements.
d. Using EXCEL, plot the transfer characteristic curve by recording as
many measurements as are necessary to create an accurate
graph.
e. On the graph, indicate the specified values of VOH (min), and VOL
(max). Note: You may do this manually (neatly) on the printed graph.
f. Print the graph and the tabulated data.
Figure 1: Set-up for TTL Transfer Characteristics
2.
Repeat the procedure above using the 4011B (CMOS) device.
3.
Demonstrate these circuits and display the graphs or values to your
instructor.
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Lab #2: TTL and CMOS Specifications
SAIT- ENT-DIGI-260
Procedure 2:
Measure power supply current
1. For the TTL device, look up the minimum and maximum values for I CCH
and ICCL in the specification sheet. Record these values in Table #1.
2. For the TTL device, measure the ICCH by connecting the gates so they all
provide a logic high, and measure ICCL by connecting the gates to provide
a logic low. Record these values in Table #1.
3. Demonstrate a sample measurement to your instructor.
4. Answer the question at the end of this lab.
Procedure 3:
Measure input currents
1. Using a 74LS00, measure gate input currents using the following
procedure:
a. Look up the typical values for IIH and IIL in the specification sheet.
Record these values in Table #2.
b. Tie one input of the gate high. Measure the current flowing into the
other input with a logic low applied, and again with a logic high
applied. Record your results in Table #2.
c. Tie both inputs of the gate together. Measure the current flowing in
these two inputs with a logic low applied, and again with a logic
high applied. Record your results in Table #2.
2. Repeat the procedure above using a 4011B. Record values in Table #3.
3. Demonstrate a sample measurement to the instructor.
4. Answer the questions at the end of this lab.
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Lab #2: TTL and CMOS Specifications
SAIT- ENT-DIGI-260
Table #1 (TTL ICCH and ICCL from procedure 2):
Specification Manufacturer spec
Measured value
ICCH Typ.
ICCH Max
ICCL Typ.
ICCL Max
Table #1: ICCH and ICCL
Table #2 (TTL IIH and IIL from procedure 3):
Specification Specification Measured Single Measured Two
Sheet
Input
Input
IIH Max
IIL Max
Table #2: IIH and IIL for TTL device
Table #3 (CMOS IIH and IIL from procedure 3):
Specification Specification Measured Single
Sheet
Input
IIH Max
IIL Max
Table #3: IIH and IIL for CMOS device
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Lab #2: TTL and CMOS Specifications
SAIT- ENT-DIGI-260
Answer the following questions.
1. In procedure 2, were your measurements within specification? Explain.
2. In procedure 3 and the TTL device, why did you get the results you did when
comparing the single gate input and the two gate input values? You will need
to use the specification sheet to aid in your explanation.
3. In procedure 3 and the CMOS device, why were the measurements
troublesome?
Signatures:
Procedure 1 circuits: ___________
Procedure 2 circuit: ___________
Procedure 3 circuits: ___________
Submission:
Submit all graphs, values and answered questions as a report. The report should
include:
 cover sheet with basic information (such as the lab number, names, date,
etc…)
 printed graphs
 measured values
 pages 4 and 5 from this lab (with instructor signatures)
Student Names: _____________
_______________ Date: ___________
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