# Difference between T-flip flop and clocked SR latch

1. Mar 22, 2013

### Bipolarity

Precisely what is the difference between the (clocked) T flip flop and clocked SR latch? I have looked at the logic diagrams for both, but am wondering about functionality differences between the two. How do they differ in their functional use?

All help is appreciated. Thanks!

BiP

2. Mar 22, 2013

### carlgrace

They have different functions. The output of a flip-flop is flipped if the input is 1 when it's clocked (i.e. if the output is 0, the next output will be 1 and vice verse). If the input is 0 then the output of the T flop doesn't change. The SR works differently. If S is set the output is 1, if R is set the output is 0 and if neither is set the output doesn't change.

3. Mar 22, 2013

### Bipolarity

OK thans, so better question:
What's the difference between an SR latch and a clocked SR latch?

BiP

4. Mar 22, 2013

### carlgrace

When it's clocked it can only change state when the clock is high. When the clock is low it can't change.

Your next question should be: what's the difference between a latch and a flip-flop (since you're using them interchangeably).

A latch can change state whenever the clock is high.

A flip-flop only changes state on a clock edge (either rising or falling, depending on how it's built)

5. Mar 24, 2013

### Bipolarity

Thanks!
How does the design of a latch differ from that of a flip flop? It seems for a latch, each input need merely be ANDED with a system clock, which when active allows the latch to change states.

But it seems designing a flip flop would not be so easy, since you want the output to change only on the edge of a clock cycle.

BiP

6. Mar 24, 2013

### carlgrace

There are several ways. The simplest way is called the "Master Slave" structure where you have a latch driven by clock in series with a latch driven by the inverted clock. Check out the wikipedia page for "flip flop" for more information.