What types of flip flops

Overview of flip-flop types

1. Non-clocked flip-flops (asynchronous FF)

A simple basic flip-flop has two inputs S and R and two outputs Q and . The input assignment has a direct effect on the state of the flip-flop (see NAND-FF or NOR-FF)

2. Clock-controlled flip-flops (synchronous FF)

Clock-dependent flip-flops also have a corresponding one Clock input. The inputs S and R only work in conjunction with the clock input (T or C. - from engl. clock). A distinction is made between two main groups, the clock state controlled and the edge-controlled Flip flops.

2.1. clock state controlled flip-flops

These flip-flops process an incoming input signal throughout Duration of the active level (e.g. C = 1).

State-controlled flip-flop:
A flip-flop whose set and reset inputs are only effective when a signal is present at the clock input.
A clock input C1 is added to the flip-flop.


Two-state controlled flip-flop:
A flip-flop that receives the input states during one clock state and only outputs them in the next clock state.
Flip-flop outputs at which the input states appear delayed are called retarded outputs. Such flip-flops work on the master-slave principle.

2.2. edge-controlled flip-flops

These flip-flops process an incoming input signal only to a specific one time, namely when the clock signal C changes its level (clock edge). A change in the clock signal from "0" to "1" is called a rising clock edge, a change in the clock signal from "1" to "0" is called a falling clock edge.

Single-edge controlled flip-flop:
A flip-flop whose set and reset inputs only take effect when the clock state is changed.
The susceptibility to interference from interfering signals is reduced by the short time of the clock edge.
The clock edge control is indicated in the circuit symbol by the triangle.

Two-edge controlled flip-flop:
A flip-flop that picks up the input states during a clock edge and only outputs them on the following edge.
In the case of the clock edge-controlled flip-flop, the susceptibility to interference is again reduced.



1. Get a flip-flop block out of the closet and check that it is one state controlled flip-flop. Create a truth table.



2. Use the website http://kauai.theoinf.tu-ilmenau.de/~sane/projekte/flipflop/flipflop.html and try to understand the English terms. Select the following flip-flop in the applet window:

Check how this specified FF circuit behaves. To do this, you can switch inputs h01, h10 and C using the corresponding buttons. A signal-time diagram is generated next to the buttons. Explain what you can read on this diagram.

Try to understand the circuit made up of 4 NAND gates. You can use the functionality of the NAND-FF as you have already learned.