Which entities specify the voltage levels in logic diagrams?

The voltage levels in logic diagrams are specified by manufacturers. This is because manufacturers define the electrical characteristics and specifications for their components, such as integrated circuits, transistors, and other digital logic elements. They provide detailed datasheets that outline the logic levels, including the minimum and maximum voltages that define logical '0s' and '1s'. This information is crucial for ensuring that different components can work together correctly within a circuit.

Understanding these specifications allows designers and engineers to create reliable systems that function as intended, making it essential for manufacturers to provide accurate and standardized voltage level information. Designers and engineers utilize this information in their work, but it is the manufacturers who set the baseline for these specifications.