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Level vs edge triggering

Short answer

Level triggering makes the output respond to inputs during the entire active clock level (HIGH or LOW), while edge triggering responds only at the instant of a clock transition (rising or falling edge). Latches use level triggering and may change multiple times per clock; flip-flops use edge triggering, changing at most once per cycle, avoiding race-around and reducing noise sensitivity.

Differentiate between level and Edge triggering?

Triggering is the way a clock signal makes a flip-flop or latch change state. In level triggering the output responds to the inputs during the whole time the clock is at its active level (HIGH or LOW). In edge triggering the output responds only at the instant of a clock transition (rising or falling edge).

CLK      ___|‾‾‾‾‾‾‾|___
Level:      [ active ]     (whole HIGH time)
+ve edge:   ^              (only at rise)
-ve edge:           v      (only at fall)
PointLevel triggeringEdge triggering
RespondsDuring whole active levelOnly at clock edge
DeviceLatch (gated SR, D latch)Flip-flop
SymbolPlain CLK / EN inputTriangle (>) at CLK; bubble for falling
Output changesMany times in one clock pulseAt most once per clock cycle
Race-aroundPossible (JK with J=K=1)Not possible
Noise sensitivityMore (any glitch during level)Less
UseSimple storage, transparent latchesCounters, shift registers, synchronous systems

Example: in a D latch with EN=1EN = 1, Q follows D continuously ("transparent"). In a positive-edge D flip-flop, Q takes the value of D only at the rising edge and holds it until the next rising edge.

✓ Answer checked by Claude Opus 5.5 (high effort)

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