Digital electronicsLesson 2 of 3 in the course Sequential logic

Digital Storage Elements: Latches, Flip-Flops, and Timing

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson introduces flip-flops and latches as basic storage elements in digital electronics. It explains how a circuit can retain one bit and why stored state matters in sequential systems.

A flip-flop or latch is a bistable circuit: it has two stable states and can remain in either state until a control signal changes it. The two states represent the binary values 0 and 1. The circuit's output commonly includes both the stored value, QQ, and its logical complement, often written as Q‾\overline{Q}.

All flashcards

How does feedback let an SR latch retain a state?
Cross-coupled gates feed their outputs back as inputs, maintaining a stable state after set or reset is removed.
How does a gated D latch behave when enabled and disabled?
It follows D while enabled and retains its previous value while disabled.
How can two opposite-phase latches produce edge-triggered behavior?
A master latch accepts data during one phase; a slave transfers it during the opposite phase.
When does a dual-edge-triggered D flip-flop capture data?
On both rising and falling clock edges.
What is a one-hot storage representation?
A representation with exactly one output high at a time.

Quiz questions

  1. For an active-high NOR SR latch, what happens when S=0 and R=0?Answer: The latch retains its previous state.
  2. In a NAND SR latch with active-low controls, what input condition normally holds the state?Answer: Both control inputs are high.
  3. When does an edge-triggered D flip-flop capture its input?Answer: At the specified active clock transition.
  4. If a T flip-flop has T held high, what is its output frequency relative to the clock?Answer: Half the clock frequency.
  5. What does a JK flip-flop do when J=1 and K=1 at the active clock edge?Answer: It toggles its stored state.

Based on the Wikipedia article Flip-flop (electronics), licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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