Xilinx - Since its founding more than 25 years ago, Xilinx has been a semiconductor industry leader at the forefront of technology, market and business achievement. Whether pioneering the fabless manufacturing model, inventing the FPGA, ranking among the world's leading patent holders, or delivering products and services distinguished by their quality and reputation for customer satisfaction, a spirit of innovation has driven the company to break new ground.Today,XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP  Xilinx is one of the world's leading providers of programmable platforms, with $1.8B in revenues in fiscal year 2010 and more than 50 percent market share in the programmable logic device segment of the semiconductor industry .XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP

Xilinx CoolRunner™-II CPLDs deliver the high speed and ease of use associated with the XC9500/XL/XV CPLD family with the extremely low power versatility of the XPLA3 family in a single CPLDXC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP. This means that the exact same parts can be used for high-speed data communications/computing systems and leading edge portable products,with the added benefit of In System Programming. Low power consumption and high-speed operation are combined into a single family that is easy to use and cost effective. Clocking techniques and other power saving features extend the users’ power budget. The design features are supported starting with Xilinx ISE® 4.1i WebPACK tool. Additional details can be found in Further Reading,XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP

Architecture Description
CoolRunner-II CPLD is a highly uniform family of fast, low power CPLDs. The underlying architecture is a traditional CPLD architecture combining macrocells into Function Blocks (FBs) interconnected with a global routing matrix,the Xilinx Advanced Interconnect Matrix (AIM).XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP The FBs use a Programmable Logic Array (PLA) configuration which allows all product terms to be routed and shared among any of the macrocells of the FB. Design software can efficiently synthesize and optimize logic that is subsequently fit to the FBs and connected with the ability to utilize a very high percentage of device resources. Design changes are easilyand automatically managed by the software,XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP which exploits the 100% routability of the Programmable Logic Array within each FB. This extremely robust building block delivers the industry’s highest pinout retention, under very broad design conditions. The architecture is explained in more detail with the discussion of the underlying FBs, logic and interconnect.The design software automatically manages these device resources so that users can express their designs using completely generic constructs without knowledge of these architectural details. More advanced users can take advantage of these details to more thoroughly understand theXC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP software’s choices and direct its results.Figure 1 shows the high-level architecture whereby FBs attach to pins and interconnect to each other within the internal interconnect matrix. Each FB contains 16 macrocells.The BSC path is the JTAG Boundary Scan Control path. The BSC and ISP block has the JTAG controller and In-System Programming Circuits.XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP

The Spartan family of PROMs provides an easy-to-use, cost-effective method for storing Spartan device configuration bitstreams.When the Spartan device is in Master Serial mode, it generates a configuration clock that drives the Spartan FPGA PROM.XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP A short access time after the rising clock edge, data appears on the PROM DATA output pin that iconnected to the Spartan device DIN pin. The Spartan device generates the appropriate number of clock pulses to complete the configuration. Once configured, it disables the PROM. When a Spartan device is in Slave Serial mode, the PROM and the Spartan device must both be clocked by an XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP incoming signal.For device programming, either the Xilinx Alliance or the Foundation series development systems compiles the Spartan device design file into a standard HEX format which is then transferred to most commercial PROM programmers.XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP

The I/O and logic functions of the Configurable Logic Block(CLB) and their associated interconnections are established by a configuration program. The program is loaded either automatically upon power up, or on command, depending on the state of the Spartan device MODE pin. In Master Serial mode, the Spartan device automatically loads the configuration program from an external memory. XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP The Spartan FPGA PROM has been designed for compatibility with the Master Serial mode. Upon power-up or reconfiguration, the Spartan device enters the Master Serial mode when the MODE pin is Low. Data is read from the PROM sequentially on a single  data line. Synchronization is provided by the rising edge of the temporary signal CCLK, which is generated during configuration. Master Serial mode provides a simple configuration interface .XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP Only a serial data line and two control lines are required to configure the Spartan device. Data from the PROM is read sequentially, accessed via the internal address and bit counters which are incremented on every valid rising edge of CCLK.XC3S250E-4PQG208I Xilinx Inc IC FPGA SPARTAN-3E 250K 208-PQFP