Microsoft Word - Digital Logic Design v_4_6a

• A pulse-triggered flip-flop is also called “master-salve” due to its implementation which
  require two D-type flip-flop in a master-salve set up as shown below:

The D flip-flop is the most commonly used bi-stable memory device. The other two kinds used are J-K

and T flip-flops.

 J-K Flip Flops
Below is a negative-edge triggered JK flip flop. As in other flip-flops, the inputs J and K are called
“excitation inputs”.

S

1J

C1

1K

R

PRE’

J

CLK

K

CLR’

Q

Q’

J K Q + Comment

0 0 Q no change

0 1 0 reset condition

1 0 1 set condition

1 1 Q’ toggle

Symbol

Characteristic equation: Q

+

= J.Q’ + K’.Q

Characteristic Table

Q

D

C

S

D

C

R

C

D

Q

Q

Q’

Set

Reset

or

S

D

C

R

Q

Q’

Set

D

C

Reset

Postponed output symbol