doubt in master-slave circuits

Discussion in 'General Electronics Chat' started by elisettynarendra, Oct 3, 2010.

  1. elisettynarendra

    Thread Starter Member

    May 17, 2010
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    in jk flip flops , o/p is connected to i/p so there arises the problem of race around condition. so we go for master slave jk flipflops to eliminate that.
    but i observed master slave design for sr flip flop's too. where sr flip flop's don't have feedback(so no chance of race around). do MS-SR flip flop have any advantages over normal sr flipflops.plz correct if i am wrong.
    [​IMG]
    [​IMG]
     
    Last edited: Oct 3, 2010
  2. Wendy

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    Mar 24, 2008
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    Anything with a master/slave configuration can be wired to toggle. Why bother otherwise? With toggling comes the ability to count. With counting comes advanced logic, as well as clocks, frequency counters, and other nifty devices.

    If you want more input you need to include a schematic.
     
  3. elisettynarendra

    Thread Starter Member

    May 17, 2010
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    but in masterslave sr flipflop we dont get a race around problem and toggle condition..we only get a toggle in jk flipflop where o/p is fedback to i/p..
     
  4. Wendy

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    You'll note the input on the schematic has a clock, what do you think I was talking about?
     
  5. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Difference is that Master-Slave flip-flops are trigered by clock edge, while single flip-flops are triggered by clock level. Thus MS are better, because the edge is one very short moment compared to the length of one logic level of the clock signal, so the transition happens more in "one exact time".
     
  6. Wendy

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    Actually a simple set/reset flip flop isn't triggered at all, at least not by a clock. There are analog ways to get around this, but in a purely digital world you have to have two flip flops (master/slave) to toggle on a pulse.

    If anyone knows any exceptions to this I'd be interested, I've put a bit of thought into it. This...

    [​IMG]

    can not be used in a counter.
     
  7. kubeek

    AAC Fanatic!

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    E is the trigger. And if you connect clock to it you can make seqential circuits.
     
  8. Wendy

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    But not count, which is the core point I've been making. You could use two of them, but then it would be a master/slave.

    Unless you know of a way to illustrate I'm wrong? I draw my examples.
     
  9. elisettynarendra

    Thread Starter Member

    May 17, 2010
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    @kubeek
    if that is the only purpose we are going for MS flipflop , if we use the circuit for 'E' , the flipflop will be triggerd at edges.
    [​IMG]
    why cant we use simpler SR circuit with this triggering ..instead we can avoid high propagation delay which occurs in case of MS-SR flipflops.
     
    Last edited: Oct 3, 2010
  10. Wendy

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    What you are looking at is a latch and hold, which has a whole different set of uses.

    Various configurations have different jobs, they do different things. Latch and hold are good for displays for example, they will keep the display still while the counters are working.

    The SR does not count, it can't. It can "remember" a previous state. It is a memory cell.

    Anytime you want a clock input you need master/slave, but counting is a different job.

    There are actually many different configurations for flip flops, each does a different job. D type flip flops are also a master slave, but they are used for shift registers.

    Try reading Wikipedia for the various types.
     
  11. elisettynarendra

    Thread Starter Member

    May 17, 2010
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    thanks bill..i will search for the other applications ..
     
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