TTL-series counters (7490,7492,7493)


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Hades Applets contents visual index introduction std_logic_1164 gatelevel circuits delay models flipflops adders and arithm... counters asynchronous... asynchronous... frequency di... synchronous ... synchronous ... up/down counter asynchrounou... 749x counters 7493 1:16 co... 7490 1:10 co... 7492 1:12 co... 74590 counter 74390 decima... frequency co... pulse-generator digital clock digital clock LFSR and selftest memories programmable logic state-machine editor misc. demos I/O and displays DCF-77 clock relays (switch-le... CMOS circuits (sw... RTLIB logic RTLIB registers Prima processor D*CORE MicroJava Pic16 cosimulation Mips R3000 cosimu... Intel MCS4 (i4004) image processing ... [Sch04] Codeumsetzer [Sch04] Addierer [Sch04] Flipflops [Sch04] Schaltwerke [Sch04] RALU, Min... [Fer05] State-Mac... [Fer05] PIC16F84/... [Fer05] Miscellan... [Fer05] Femtojava FreeTTS		TTL-series counters (7490,7492,7493) The image above shows a thumbnail of the interactive Java applet embedded into this page. Unfortunately, your browser is not Java-aware or Java is disabled in the browser preferences. To start the applet, please enable Java and reload this page. (You might have to restart the browser.) Circuit Description This applet demonstrates the 749x counters from the TTL-series or HC-series of (small-scale) integrated circuits. The most popular counter ICs from the 74xx series are the following, each of which is included in the applet: 7490, a 1:10 counter which can be split into 1:2 and 1:5 7492, a 1:12 counter which can be split into 1:2 and 1:6 7493, a 1:16 counter which can be split into 1:2 and 1:8 All three ICs are based on JK flipflops and feature asynchronous reset inputs. The first counter stage uses separate input and output pins, and can be used as a standalone 1:2 counter stage. The remaing three stages are connected internally, so that the carry and feedback paths are not accessible from the outside. To connect both stages, the A output of the first stage is connected to the CB input of the next stage(s). Note the curious 0-1-2-3-4-5-8-9-a-b-c-d count-sequence of the 7492. Exercise: Describe how to realize the missing counters (e.g., 1:3, 1:7, 1:9) with the 749x integrated circuits.

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Impressum		http://tams.informatik.uni-hamburg.de/applets/hades/webdemos/30-counters/60-ttl/749x.html