PDA

View Full Version : What is the difference between flip-flops?



MoChebs
17-02-2005, 08:49 AM
Hi, I would like to know what the major difference between the RS, D, and JK flip-flops are. I've looked for major differences but can't seem to find anything significant.


Thanks for the help!

bartsdadhomer
17-02-2005, 11:28 AM
Fairly good explaination on these links
Been ages since I even thought about a flip flop so the revision was good for me as well
http://computer.howstuffworks.com/boolean3.htm
http://www.cs.umd.edu/class/spring2003/cmsc311/Notes/Seq/flip.html
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/jkflipflop.html
http://www.nottingham.ac.uk/physics/ugrad/courses/mod_home/f31ylc/elecexpts/logic/logic2.htm

Graham L
17-02-2005, 12:22 PM
D is my favourite. It's edge triggered. Whatever is on the data input when the clock goes high is latched. D logic is what makes a traditional mouse (with the little opto-interruptors) work. There were a huge number of them in the CPU of a PDP8.

RS is set/reset : set input gives "set" output; reset input gives "reset". (most D-type have set and reset inputs). Useful for pushbuttons.

J-K is complicated. You need to study the truth table. It's level, not edge, clocked, so is sometimes less susceptible to noise than a D. People who like complicated circuits love J-K.

I was once supposed to follow a design by a comedian who had made a dual latch out of AND-OR-INVERT gates. One latch gave a high, the other a low output from high inputs. I put in a 7474, and got a choice of either (or both).