D-Latch is a simple clocked memory element in which the output is equal to the s
ID: 3573838 • Letter: D
Question
D-Latch is a simple clocked memory element in which the output is equal to the stored state inside the element.
In D-Latch the state is changed whenever the appropriate inputs change and the clock is asserted. A D-Latch has two inputs and two outputs.
The inputs are the data value to be stored and a clock signal that indicates when the latch should read the value on the data input and store it. The outputs are simply the value of the internal state and its complement.
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When the clock input is asserted, the latch is said to be open, and the value of the output becomes the value of the data input. When the clock input is de-asserted, the latch is said to be closed, and the value of the output is whatever value was stored the last time the latch was open.
What is the difference between DFF and D-Latch? Your response should be a minimum of 75 words or more. A summary of your understanding of what a DFF and D-latch is after reading and watch the course material this week.
Can one chip be used for constructing the other? Explain. Your response needs to be in your own words at a minimum of 75 words.
Explanation / Answer
The latches are transparent in the enable configuration, i.e. if the latch is enabled the output Q will follow the input D for all changes in D .The D latch is used to capture, or 'latch' the logic level which is present on the Data line when the clock input is high. When the data on the D line changes state when the clock pulse is high, then the output, Q, follows the input, D. When the CLK input falls to logic 0, the last state of the D input is trapped and held in the latch.Latch is also aschynchronous.Thus they are not triggered at all.
Mean while , flip-flops are edge triggered. The output Q will only follow D at the edge of the clock; whether it be rising or falling edge is dependant on the flip flop design.The working of D flip flop is similar to the D latch except that the output of D Flip Flop takes the state of the D input at the moment of a positive edge at the clock pin (or negative edge if the clock input is active low) and delays it by one clock cycle. That's why, it is commonly known as a delay flip flop. The D FlipFlop can be interpreted as a delay line or zero order hold. 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 be ignored until the next clock event.
Latches can be build flip flops.latches can be built from gates, and flip-flops can be built from latches.Latches are asynchronous, which means that the output changes very soon after the input changes. Most computers today, on the other hand, are synchronous, which means that the outputs of all the sequential circuits change simultaneously to the rhythm of a global clock signal.A flip-flop is a synchronous version of the latch. Thus latches can be combined and made a flip flop.
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