In: Electrical Engineering
Read sections in the TTL data sheets pertaining to the 74LS112A Dual J-K flip-flop.
1. For the 74LS112A, what is the maximum clock rate, minimum pulse width for the clock’s high and low levels, worst case propagation delay of the outputs from the high-to-low clock transition, and minimum input setup time?
2. Design a nine-step counter to count in the following sequence. Use J-K flip-flops, NAND gates, and Inverters only.
0011, 0101, 1001, 1000, 1011, 1010, 0110, 0100, 0111, 0011, …
Include in the design a means for resetting the counter to 0011.
Provide a circuit diagrams, relevant truth tables, state diagrams and state table.
In addition, provide the excitation functions for the J-K flip-flops.
1. Following are the data of 74LS112A for RL = 2kohm, TA = 25 degree Celcius, VCC = 5V and for two different values of CL
Parameter | CL = 15pF | CL = 50pF |
Maximum clock rate | 30MHz | 25MHz |
Minimum pulse width for clock high and low | 20ns | 25ns |
Worst case propogation delay tPHL | 20ns | 28ns |
Worst case propogation delay tPLH | 20ns | 24ns |
Minimum setup time | 20ns | 25ns |
2. Nine step counter
State diagram
State Table
Present State |
Next State |
||||||
QA |
QB |
QC |
QD |
QA+1 |
QB+1 |
QC+1 |
QD+1 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
1 |
0 |
1 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
0 |
1 |
0 |
1 |
1 |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
0 |
1 |
1 |
1 |
0 |
0 |
0 |
1 |
0 |
1 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
1 |
0 |
1 |
1 |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
0 |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
1 |
0 |
0 |
1 |
1 |
Excitation table of JK Flipflop
Q |
Q+ |
J |
K |
0 |
0 |
0 |
X |
0 |
1 |
1 |
X |
1 |
0 |
X |
1 |
1 |
1 |
X |
0 |
Including the J K inputs in the state table
Present State |
Next State |
Flip flop inputs |
|||||||||||||
QA |
QB |
QC |
QD |
QA+1 |
QB+1 |
QC+1 |
QD+1 |
JA |
KA |
JB |
KB |
JC |
KC |
JD |
KD |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
X |
0 |
X |
1 |
X |
1 |
X |
0 |
0 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
X |
0 |
X |
1 |
X |
X |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
0 |
X |
0 |
X |
X |
0 |
1 |
X |
0 |
0 |
1 |
1 |
0 |
1 |
0 |
1 |
0 |
X |
1 |
X |
X |
1 |
X |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
X |
X |
0 |
1 |
X |
1 |
X |
0 |
1 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
X |
X |
1 |
0 |
X |
X |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
0 |
0 |
0 |
X |
X |
0 |
X |
1 |
0 |
X |
0 |
1 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
X |
X |
1 |
X |
0 |
X |
0 |
1 |
0 |
0 |
0 |
1 |
0 |
1 |
1 |
X |
0 |
0 |
X |
1 |
X |
1 |
X |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
X |
0 |
0 |
X |
0 |
X |
X |
1 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
X |
1 |
1 |
X |
X |
0 |
0 |
X |
1 |
0 |
1 |
1 |
1 |
0 |
1 |
0 |
X |
0 |
X |
1 |
X |
0 |
X |
1 |
1 |
1 |
0 |
0 |
0 |
0 |
1 |
1 |
X |
1 |
X |
1 |
1 |
X |
1 |
X |
1 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
X |
1 |
X |
1 |
1 |
X |
X |
0 |
1 |
1 |
1 |
0 |
0 |
0 |
1 |
1 |
X |
1 |
X |
1 |
X |
0 |
1 |
X |
1 |
1 |
1 |
1 |
0 |
0 |
1 |
1 |
X |
1 |
X |
1 |
X |
0 |
X |
0 |
K - maps
Circuit Diagram