Sequential Circuits (1)

Digital systems operate using logic. Logic involves the use of binary

variables. A binary variable can have only two possible values. In digital circuits, the binary variable is a voltage. Typically, a 5 V power supply is used in digital circuits.

A low voltage of 0 V represents logic 0.

A high voltage of +5 V represents logic 1.

Digital circuits can be:

combinational – the output of the circuit is determined by the

current inputs.

sequential – the output of the circuit is determined by the current

inputs and previous outputs.

Sequential digital circuits are classified as:

synchronous – a clock input is used to drive all the circuit operations.

asynchronous – the circuit operations are driven by changes in the

input signals.