# D type Flip Flop

Discussion in 'Electronic Basics' started by Chris W, Feb 17, 2005.

1. ### Chris WGuest

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

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2. ### John PopelishGuest

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.
http://rocky.digikey.com/WebLib/Texas Instruments/Web data/CD4013B.pdf
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.
http://rocky.digikey.com/WebLib/Texas Instruments/Web data/CD4042B.pdf
It has a clock polarity input that lets you chose which edge flips the
flops.
Yes.

3. ### Chris WGuest

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

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

4. ### Jonathan KirwanGuest

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

5. ### Rich GriseGuest

He wants a whole bunch of T flip-flops in one package. The most I've ever
seen is 2. ("T" is for "Toggle".)

Although, it could be done with a microprocessor (if it doesn't have to
be fast) or some kind of gate array.

Cheers!
Rich