páginas desderadio electronics february 1992

staying high for on e full clock cycle. T he CARRY OU T goes high for on e clock cycle ou t of every 10 clock cycles, a n d it ca n be used to ripple-count more C040l7B s in a multi-decade counting application. T h e counting cycle is inhibited by setting CLOCK INHIBIT high. A high on the RESET input clears t he counter, and sets th e 0 - output high. DECODED DECIM l OUTPUTS 0 3 1 2 2 4 3 7 4 10 5 1 6 5 8 9 9 11 CARRY 12 OUT 16 IC CD D 7B 8V 55 13 CLOCK INHIBIT 15 RESET 14 CLOCK FIG. 1 PINOUTS OF THE CD4 cade counter/divider with its d llCodEd outputs shown In ascending arit melle or der.TheclockIsInhibitedbyahig h on pin 13 and the counter is re et by a H gh on pin 15 and advances on a posltiY going clock transiti on. WIT Chaser principles On e of t h e most popula ED displays is known a s a c h a se r, also called a sequencer. T h d t s when a n IC drives a n LED arra s o that each LE D or smal groups thereof) turns o n and off i n a fixed, periodic sequence, that appears a s a ripple of light running along a chain. T h e LED s don t necessarily have to be arranged linearly, a n d c a n be placed in a ny desired geometric pattern, to alter the visual effect. T he most popular CMOS IC which is used for that purpose is the CD40l7B, which is a decade counter/divider IC with 10 decoded outputs, each capable o f directly driving an LED d is - play. If desired, th e outputs be coupled back to th e IC con- trol terminals to make the de- vice count to (or divide by) an y number from 2 9 a nd either stop or recycle. T h e CD4017B is easily cas caded for u s e in multi-decade frequency division, or for use in counters with any number of decoded outputs. It s extremely versatile, a n d it c a n easily b e

páginas desderadio electronics february 1992

Documents