ch. 12 : counter circuits &...

Ch. 12 : Counter Circuits& Applications

OutlineOutline

Analysis of Sequential CircuitsRipple counters

fDesign of Divide-by-N CountersRipple Counter ICs

lSystem Design Applications7-Segment LED Display DecodersS h C tSynchronous CountersSynchronous Up/Down-Counters ICsA li ti f S h C t IC

Ch. 12: Counter Circuits 2

Applications of Synchronous Counters ICs

12.1 Analysis of Sequential y qCircuits

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12 2 Ripple counters12.2 Ripple countersA counter circuit can be built by cascading flip-flops together. (Connecting the Q output of one flip flop to the clock input of the(Connecting the Q output of one flip-flop to the clock input of the next) The number of states in a counter (modulus) is 2N where N is the number of flip-flops.number of flip flops. In order for a counter to operate properly each flip-flop must toggle. For J-K flip-flops this means both J and K must be high. In a ripple counter the clock input has to propagate through each pp p p p g gflip-flop of the counter. A ripple counter is also called an asynchronous counter because each flip-flop does not change at the same time. The propagation delay of each flip-flop adds together to give a total propagation delay for the counter. This propagation delay will limit the maximum frequency allowed by the input trigger clock. A down counter can be formed by taking the output from the


A down counter can be formed by taking the output from the output instead of the Q output of each flip-flop.

Three bit binary ripple counterThree bit binary ripple counter


Effect of propagation DelayEffect of propagation Delay


Down Counter (Exp: Mod 8)Down Counter (Exp: Mod 8)


12.3 Design of Divide-by-N g yCounters

A counter can also be used as a frequency divider. q y


Mod 6 : 7 6 5 4 3 2 7 6 5Mod 6 : 7,6,5,4,3,2,7,6,5,…


Count 0,1,2,3,4,5 and then , , , , ,stops and turns on an LED


12 4 Ripple Counter ICs12.4 Ripple Counter ICs

7490 (mod 2 x 5)7492 (mod 2 x 6)7492 (mod 2 x 6)7493 (mod 2 x 8)


74937493


74907490


74927492


12 5 System Design Applications12.5 System Design Applications

Digital ClockTimer UpTimer UpTimer Down


Di it l Cl kDigital Clock


Timer up till 3 minuteTimer up till 3 minute


12.6 7-Segment LED Display g p yDecoders

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12 7 Synchronous Counters12.7 Synchronous Counters

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12.8 Synchronous Up/Down-y pCounters ICs

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12.9 Applications of ppSynchronous Counters ICs

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KuisKuis

Count up 34563456, 4567845678Count down 65436543: 8765487654Count down 65436543: 8765487654Timer up 012345 : 012345678Ti d 543210 876543210Timer down 543210: 876543210


Tugas Kamis jam 0:00Tugas Kamis jam 0:00

Timer down, start pada 2 digit terakhir NPM, berhenti saat 00Jam digital 24an (23:59) menggunakan 7493

Timer down start 5:00, 4:59, … berhenti 0:00


ch. 12 : counter circuits &...

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