Flip-flops: Toggle (T)

T (toggle) flip-flop holds the value of Q when input T is 0, and toggles when T is 1

Characteristic table for T (toggle) flip-flop:

T

Q

Q+

Operation

0

0

0

hold

0

1

1

hold

1

0

1

toggle

1

1

0

toggle

Is this really XOR in disguise?

Inputs of XOR

2 operands

Inputs of T flip-flop

toggle (T)

clock

current state (Q)

Input Q and output Q+ are really the same output, but at different times

When output changes

Flip-flop can change only at positive clock edge

XOR can change whenever inputs change