D type Flip Flop

Feb 17, 2005 3 Replies
C

Let me see if I understand this. If I were to take a D Flip Flop and connect the Q' output to the D input, every time the clock input fell from 1 to 0, the state of the Q output would be opposite of what it was? Is there a way to change this so the Q output changes as the clock rises from 0 to 1? Also can someone recommend a part number at Mouser or digikey for an IC that has from 4 8 or 16 D flip flops that can be hooked up this way? The ones I have seen don't have the Q' output, so it would require the addition of an inverter.


Chris W Gift Giving Made Easy Get the gifts you want & give the gifts they want http://thewishzone.com "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -- Benjamin Franklin, 1759 Historical Review of Pennsylvania
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C

That looks like what I asked for, thanks!

No I need the clocks and Qs to be independent. However, a common reset pin like I have seen on some of them would be nice.

I guess I should tell what I am really after. I want a chip that alternates the outputs when the inputs rise from 0 to 1. With each input and output independent of each other. I want as many of them in a single DIP as I can get (well up to 16 anyway). A global reset would be a nice too. I can do that with the one you sent the link to, by hooking it up right and using 8 of them. But it would be nice if I could find one that is already hooked up that way.

Chris W Gift Giving Made Easy Get the gifts you want & give the gifts they want http://thewishzone.com "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -- Benjamin Franklin, 1759 Historical Review of Pennsylvania
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J

Some D flip flops clock on the falling edge and some clock on the rising edge. The CD4013 dual D clocks on the rising edge.

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I think that most chips with more than 2 D flip flops have a common clock that clocks all or groups of them. Is that okay?

If so, look at the CD4042.

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It has a clock polarity input that lets you chose which edge flips the flops.

Yes.

John Popelish
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J

How is this different from a simple JK flipflop? Examine the SN74HC109, for example, and consider the J=1, \k=0, with your input tied to the clock (CLK).

Jon

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