avte 221
Espinosa, Richard Anderson A. February 6, 2014
AVTE 221 – 4C Mr. Jimmy Marcaida II
Assignment:
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. A flip-flop is a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Flip-flops and latches are a fundamental building block of digital electronics systems used in computers, communications, and many other types of systems.
D flip-flop
D flip-flop symbol
The D flip-flop is widely used. It is also known as a "data" or "delay" flip-flop. The D flip-flop captures the value of the D-input at a definite portion of the clock cycle (such as the rising edge of the clock). That captured value becomes the Q output. At other times, the output Q does not change. The D flip-flop can be viewed as a memory cell, a zero-order hold, or a delay line.
Truth table:
Clock
D
Qnext
Rising edge
0
0
Rising edge
1
1
Non-Rising
X
Q
('X' denotes a Don't care condition, meaning the signal is irrelevant)
Most D-type flip-flops in ICs have the capability to be forced to the set or reset state (which ignores the D and clock inputs), much like an SR flip-flop. Usually, the illegal S = R = 1 condition is resolved in D-type flip-flops. By setting S = R = 0, the flip-flop can be used as described above. Here is the truth table for the others S and R possible configurations:
Inputs
Outputs
S
R
D
>
Q
Q'
0
1
X
X
0
1
1
0
X
X
1
0
1
1
X
X
1
1
These flip-flops are very useful, as they form the basis for shift registers, which are an essential part of many electronic devices. The advantage of the D flip-flop over the D-type "transparent latch" is that the signal on the D input pin is captured the moment the flip-flop is clocked, and subsequent changes on the D input will
AVTE 221 – 4C Mr. Jimmy Marcaida II
Assignment:
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. A flip-flop is a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Flip-flops and latches are a fundamental building block of digital electronics systems used in computers, communications, and many other types of systems.
D flip-flop
D flip-flop symbol
The D flip-flop is widely used. It is also known as a "data" or "delay" flip-flop. The D flip-flop captures the value of the D-input at a definite portion of the clock cycle (such as the rising edge of the clock). That captured value becomes the Q output. At other times, the output Q does not change. The D flip-flop can be viewed as a memory cell, a zero-order hold, or a delay line.
Truth table:
Clock
D
Qnext
Rising edge
0
0
Rising edge
1
1
Non-Rising
X
Q
('X' denotes a Don't care condition, meaning the signal is irrelevant)
Most D-type flip-flops in ICs have the capability to be forced to the set or reset state (which ignores the D and clock inputs), much like an SR flip-flop. Usually, the illegal S = R = 1 condition is resolved in D-type flip-flops. By setting S = R = 0, the flip-flop can be used as described above. Here is the truth table for the others S and R possible configurations:
Inputs
Outputs
S
R
D
>
Q
Q'
0
1
X
X
0
1
1
0
X
X
1
0
1
1
X
X
1
1
These flip-flops are very useful, as they form the basis for shift registers, which are an essential part of many electronic devices. The advantage of the D flip-flop over the D-type "transparent latch" is that the signal on the D input pin is captured the moment the flip-flop is clocked, and subsequent changes on the D input will