Extended Information

CPLDs (Complex Programmable Logic Devices) differ structurally from early SPLDs that relied on basic logic gate programming. CPLDs, instead, use logic block programming based on product term technology, alongside EPROM or Flash memory technologies. They can not only implement various forms of sequential logic control but are also well-suited for complex combinational logic circuits. CPLD products vary widely in design, and the device structures differ significantly across manufacturers. However, most companies' CPLDs still utilize array-type unit structures based on product terms. For example, Altera's MAX series, most of Lattice's products, and Xilinx's XC9500 series all use programmable product term array structures.