Logic Circuit: 3 State Buffer (1)

Case of H level
Figure 1. Case of H level

In general logic elements, the output signal is determined by the input signal, and is in either the "1" or "0" state.
However, some logic elements have another state besides "1" and "0".

For example, the circuit in the right figure is similar to the NOT circuit, but different form the NOT circuit. The NOT circuit outputs data by inverting the input signal, this circuit outputs the input data as it is.

Case of L level
Figure 2. Case of L level

If the control part is set to “1” (H level), the input data is output as it is.
However, if the control part is set to “0” (L level) as shown in Figure 2, the output part will be disconnected and the data will not be output. This disconnected state is called the high impedance.

Like this circuit, a circuit that can be taken in the three types of output state such as the "1" (H level) state, the "0" (L level) state, and the high impedance state, is called a three-state or "Tri state".

Chapter 1 Basics of Digital Circuits

Digital Value
Digital Value: Binary and Decimal
Digital Value: Units of Binary Data
Digital Value: Notation Method of Data
Digital Value: Conversion Method of the Data
Logic Circuit
Logic Circuit: AND Circuit
Logic Circuit: OR Circuit
Logic Circuit: NOT Circuit
Logic Circuit: Exclusive OR (XOR) Circuit
Logic Circuit: 3 State Buffer (2)
Logic Circuit: Application Example of Logic Circuits
Logic Circuit: RS flip-flop Circuit