Circuit Design: Know It All

Chapter 28

Complex Programmable Logic Devices (CPLDs)

Bob Zeidman

Complex programmable logic devices are exactly what they claim to be: logic devices that are complex and programmable. There are two main engineering features to understand about CPLDs that separate them from their cousins, FPGAs. One feature is the internal architecture of the device and how this architecture implements various logic functions. The second feature is the semiconductor technology that allows the devices to be programmed and allows various structures in the device to be connected.

28.1 CPLD Architectures

Essentially, CPLDs are designed to appear just like a large number of PALs in a single chip, connected to each other through a crosspoint switch. This architecture made ...