First introduced in 1998, the Spartan™ family was the world’s first FPGA series tailored for low-cost applications. With the introduction of the Spartan-3E family, Xilinx® now has seven families of Spartan FPGAs in production – with more than 100 million units shipped to date. The Spartan series features the world’s most accepted low-cost FPGA architecture and is familiar to thousands of engineers.

Moore’s law allows Xilinx to offer ever-lower prices in the Spartan series of FPGAs. The Spartan-3E family is our third Spartan family in 90 nm, and gives us the lowest possible manufacturing costs. These low costs make programmable logic successful in high-volume and low-cost production applications, an area previously reserved for ASIC and gate-array technologies.

The Spartan-3 family (introduced in 2003) is optimized for I/O-centric designs, and is ideally suited for systems that have large I/O requirements. The Spartan-3E family is optimized for gate-centric designs, and is well-suited for designs that require a relative higher gate-to-I/O ratio. The older Spartan-II/IIE and Spartan-XL families remain suitable candidates for legacy designs or for systems with higher core voltages.

Spartan-3 FPGAs have found remarkable success in the production of systems that typically would have used an ASIC or gate array. For example, many flat-panel display systems employ Spartan-3 devices to manage the display driver and control functions. The ability to modify the design after layout and adapt the system to changing market conditions makes FPGAs highly desirable.

Spartan-3E devices extend the reach of FPGAs into production volumes by further reducing costs, while preserving the low NRE and high flexibility of programmable logic. Many mainstream applications using Spartan-3E FPGAs will have an ASIC crossover point of 250,000 units – meaning that the total cost favors Spartan-3E devices over ASICs for the first quarter-million units of production.

The Spartan-3E Family
The Spartan-3E family is our newest low-cost FPGA family, and further reduces the price points for low-cost FPGAs to unprecedented levels. Through 90 nm process technology, 300 mm wafers, and application-driven architecture choices, Xilinx has extended FPGAs into volumes and applications previously reserved for mask-programmed ASICs. Spartan-3E devices offer one of the lowest costs-per-logic (CPL) of any FPGA.

Spartan-3E FPGAs have been architected for digital consumer applications, and all high-volume/low-cost applications will benefit from its advanced features and capabilities.

The five-member family ranges from the 100,000-gate XC3S100E through the 1.6 million-gate XC3S1600E, adding features such as 64/66 PCI, mini LVDS, and faster embedded multipliers for lowcost DSP, all to better serve low-cost applications. Table 1 highlights the key features of the Spartan-3E family.

The Gate-Centric FPGA
Spartan-3E devices feature an optimized inline I/O ring for the absolute lowest cost. Figure 1 shows the inline I/O ring of Spartan-3E FPGAs versus the staggered I/O pad approach used by Spartan-3 devices. Inline I/Os are more efficient for smaller densities and allow us to add more logic for a given I/O count, as shown in Figure 2.

To further reduce die size, we refined the I/O layout, removed some less-common I/O standards, and resized the output buffers. Even a small area reduction in each I/O adds up to a relatively large savings because it is repeated for each I/O pad. Many of the decisions in the Spartan-3E architecture were driven by direct feedback from our high-volume and low-cost customers.

Spartan-3E FPGAs have a lower CPL compared to Spartan-3 devices and are the lowest cost FPGAs for gate-centric designs. Correspondingly, Spartan-3 devices are well suited for I/O-intensive FPGA designs. Together, Spartan-3 and Spartan-3E FPGAs will continue to meet customer needs in low-cost system design.

New Features in Spartan-3E Devices
Besides the optimized inline I/O ring to lower costs, Spartan-3E FPGAs also have a host of new features that include:

• Support for low-cost commodity Flash memory (SPI/BPI) configuration memory
• PCI 64/66 and PCI-X support
• DDR 333 memory interface
• Mini-LVDS, RSDS
• DCM clock frequency input range expanded down to 5 MHz (ideal for video)
• 325 MHz multipliers aligned with block RAM for low-cost DSP

Conclusion
With the arrival of the Spartan-3E FPGA family, there are now even more reasons to consider programmable logic in the production of low-cost systems. With prices starting under $2 and a substantially lower cost configuration solution, Spartan-3E devices will serve as the production solution for increasing numbers of low-cost, high-volume, and consumer applications.

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