Week of December 3

Week of December 3 - Class notes for the week of December...

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Figure : D flip-flop truth table Class notes for the week of December 3 rd D type flip-flop Another common logic element is the flip- flop. Unlike any circuits we have encountered so far, flip-flops have an edge sensitive input (the clock input). Edge sensitive inputs detect a transition (or edge) between logic levels. Our clock input is sensitive only to the rising edge (a low to high transition) of the clock signal. The occurrence of a rising edge is indicated on a truth table with an upward pointing arrow. What the D flip-flop does is to transfer the value at the D input to the Q output at the instant when the clock input transitions from low to high. At all other times the Q output retains its previous value, unless the clear or preset input is asserted. The clear input will force Q to 0, while the preset will force Q to 1. Note that the clear and preset input are active low, a logical 0 must be applied to assert these inputs and clear or reset the flip- flop. As with the RS latch, asserting clear and preset at the same time is forbidden and
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This note was uploaded on 09/26/2008 for the course ESE 123 taught by Professor Westerfield during the Fall '07 term at SUNY Stony Brook.

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Week of December 3 - Class notes for the week of December...

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