Chapter 11 - Digital Integrated Circuits II

Abstract

This chapter discusses the logic gates of digital integrated circuits (ICs). There are two families of ICs that are used in digital electronics, the easy to handle variety that require a stable operating voltage of 5V, and the second category of digital ICs operate over a wide range of voltages. The 7400 series of digital ICs require a fixed 5V power supply and the 7400 series belong to the family of digital ICs known as transistor-transistor logic (TTL) devices. The first two digits of any device in the family, indicate that the device is a member of the family, while the last two digits (such as –00) indicate which IC this is in the family. This means that a 7400 (an IC with four two-input NAND gates) is different to a 7402 (an IC which has four two-input NOR gates). When there is a family of digital integrated circuits that contain logic gates, it becomes easier to build more complex digital circuits. Digital circuits can be made to remember logic states and store binary information; such family of devices that do this function in digital electronics are known as bistable circuits.