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.
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Clocked D Flip-Flop:
Clocked D Flip-Flop:A D flip-flop constructed from a NAND-latch .
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhS9eh8X_MTsHeegqqQHOcC4EC2Pu76ENEwycUXCOqBrjx7clejwgJGbl2dfHJ8dUf0BFLMrrP0JVjv7Fef7REaeclbKnErwTdy4FMONHmVo3WDOJg4RYv63a6eCNMsIHJtGoF6SgduOew/s400/Clocked+D+Flip-Flop.gif)
D Flip-Flop from NAND Latch:
The output Q will track the input D so long as the flip-flop remains enabled.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKnuCnBcU4kLvHFYIvSha94kPv2bMoLaWggKGZjR3RsiEtlK91ewqsesQDWSHiC6XeJaOpWL_LoflHeV4VtHdUCxMxZw4rqi2v-UGoWYgAArBcy_HfqVikCuHA6Ftd5Dymsz30WhR9MBA/s400/D+Flip+Flop+NAND.gif)
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.
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