The D Flip-Flop

The D flip-flop tracks the input, making transitions with match those of the input D. The D stands for "data"; this flip-flop stores the value that is on the data line. It can be thought of as a basic memory cell. A D flip-flop can be made from a set/reset flip-flop by tying the set to the reset through an inverter. The result may be clocked.

Construction from NAND-latch
Flip-Flops
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Electronics concepts

Digital circuits

Sequential Operations
 
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D Flip-Flop from NAND Latch

The output Q will track the input D so long as the flip-flop remains enabled.

Clocked VersionNAND-latchNAND Gate
Flip-Flops
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Clocked D Flip-Flop

A D flip-flop constructed from a NAND-latch .

Output Example
Flip-Flops
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Example Ouput: Clocked D Flip-Flop

The D flip-flop tries to follow the input D but cannot make the required transitions unless it is enabled by the clock. Note that if the clock is low when a transition in D occurs, the tracking transiton in Q occurs at the next upward transition of the clock.

Flip-Flops
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Electronics concepts

Digital circuits

Data Transfer

J-K Flip-Flop Applications

Reference
Tocci
Digital Systems, Sec 5-7
 
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