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Latch vs. Flip-Flop

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Latch and flip-flop are related — but not quite the same

D LATCH — LEVEL SENSITIVE DQ EN While EN is active, Q may follow D. transparent while enabled D FLIP-FLOP — EDGE TRIGGERED DQ CLK Q changes only at the selected clock edge. captures a moment in time Latch: responds during a level. Flip-flop: responds at an edge.

Latch: level-sensitive

A latch commonly has an Enable or similar control. While that control is active, the output may respond to changes at its data input. When the control becomes inactive, the latch holds the last state.

Flip-flop: edge-triggered

A flip-flop commonly changes state only at a particular transition — a rising edge or falling edge of a clock signal.

Between those edges, the stored output remains unchanged.

A camera analogy

A level-sensitive latch is like a window that is open for a while: changes can pass through while it is open.

An edge-triggered flip-flop is more like a camera shutter: it captures the input at a particular instant.

Terminology is not perfectly historical

Modern digital design usually keeps the distinction above, but older books and informal speech sometimes use flip-flop more broadly for bistable memory circuits. Context matters.

Try these yourself

A latch is generally described as: D LATCH — LEVEL SENSITIVE DQ EN While EN is active, Q may follow D. transparent while enabled D FLIP-FLOP — EDGE TRIGGERED DQ CLK Q changes only at the selected clock edge. captures a moment in time Latch: responds during a level. Flip-flop: responds at an edge.
In modern digital terminology, a latch is generally level-sensitive.
A flip-flop is generally described as:
A flip-flop generally samples or changes state at a selected clock edge.
Why can the terminology be confusing in older material?
Historical and informal usage is not always as strict as the common modern distinction.
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