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Digital Electronics: Principles, Devices and Applications

Digital Electronics: Principles, Devices and Applications

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Flip-Flops <strong>and</strong> Related <strong>Devices</strong> 375S1QR2Q —(a)SQRSFFRQ —(b)OperationModeNo changeSETRESETForbiddenS1010R1100Qn+1Qn10—(c)Figure 10.17R-S flip-flop with active LOW inputs.10.3.2 R-S Flip-Flop with Active HIGH InputsFigure 10.18(a) shows another NAND gate implementation of the R-S flip-flop. Figures 10.18(b) <strong>and</strong>(c) respectively show its circuit symbol <strong>and</strong> function table. Such a circuit would have active HIGHinputs. The input combination R = S = 1 would be forbidden as SET <strong>and</strong> RESET inputs in an R-Sflip-flop cannot be active at the same time.

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