Construction and Applications of Digital Systems
Consider the CMOS logic family and identify:
a) the different logic within the family
b) characteristics of the logic family such as:
• Propogation delay
• voltage inputs\outputs
• fan out
• Current inputs\outputs
• Voltage supply
c) the level of integration
the benefits of using CMOS against other families
The circuit below is a seven segment BCD counting circuit
R1-R77470 Ohm 1/4 Watt Resistor
U1174LS90 TTL BCD Counter IC
U2174LS47 TTL Seven Segment Display Driver IC
DISP11Common Anode 7 Segment LED Display
MISC1Board, Sockets For ICs, Wire
Counter Decoder\Driver Display
The circuit above consists of TTL logic. You are required to test and build a BCD counting display circuit using CMOS logic, Identify which IC’s are required and download data sheets for each IC including the seven segment display. Identify the type of seven segment display required either common anode or common cathode.
Construct the circuit on multisim use a function generator for the input pulses. Check your circuit works.
Construct the circuit on bread board.
[You can add more digits by building a second (or third, or fourth, etc...) circuit and connecting the pin 11-6 junction of the 74LS90 and 74LS47 to pin 14 of the 74LS90 in the other circuit. You can keep expanding this way to as many digits as you want.]
Test the circuit above taking into account all logic levels; circuit voltage and circuit current. Compare your tests to circuit specifications using the data sheets for the BCD counter IC and the Display Driver IC. Use truth tables to complement your testing procedure.
Construct a combinational full adder circuit from a digital arithmetic system. Using CMOS IC’s
D2 Evaluate and suggest improvements to the circuit operation of a digital system with respect to the method of data acquisition and human interface employed.
Take into account the alarm system you have used in Measurement & Test and Fault Finding.
Consider and evaluate how the system operates in terms of acquiring the data and presenting the outcomes within its operation , suggest improvements that could be made.
Consider the human interaction with the circuit and suggest improvements.