ATF1508AS

The ATF1508AS is a high performance, high density Complex Programmable Logic Device (CPLD) which utilizes Atmel's proven electrically erasable Flash memory technology. With 128 logic macrocells and up to 100 inputs, it easily inte-grates logic from several TTL, SSI, MSI, LSI and classic PLDs. The ATF-1508AS's enhanced routing switch matrices increase usable gate count, and increase odds of successful pin-locked design modifications.


The ATF1508AS has up to 96 bi-directional I/O pins and 4 dedicated input pins, depending on the type of device package selected. Each dedicated pin can also serve as a global control signal; register clock, register reset or output enable. Each of these control signals can be selected for use individually within each macrocell.


Each of the 128 macrocells generates a buried feedback,which goes to the global bus. Each input and I/O pin also feeds into the global bus. The switch matrix in each logic block then selects 40 individual signals from the global bus.Each macrocell also generates a foldback logic term, which goes to a regio-nal bus. Cascade logic between macrocells in the ATF1508AS allows fast, efficient generation of complex logic functions. The ATF1508AS contains eight suchlogic chains, each capable of creating sum term logic with a fan in of up to 40 product terms The ATF1508AS macrocell, shown in Figure 1, is flexible enough to support highly complex logic functions operating at high speed.  The macrocell consists of five sections:product terms and product term sel-ect multiplexer; OR/XO-R/CASCADE logic; a flip-flop; output select and enable; and logic array inputs.