The Xilinx XC3S50AN-4TQG144C is a member of the Spartan-3AN FPGA family, combining the features of the Spartan-3A platform with in-system Flash memory for configuration and nonvolatile data storage. Built on 90 nm CMOS technology and operating at a core voltage of 1.2 V, this device eliminates the need for external configuration PROMs, enabling single-chip board designs for space-conscious applications.

Nonvolatile Advantage

The Spartan-3AN family integrates 4 Mb of embedded Flash memory, which stores the FPGA configuration bitstream internally. This eliminates the need for external PROMs, reduces board space, lowers system cost, and enhances design security. The Flash memory can also be used for user data storage, code shadowing, or scratchpad memory in embedded processing applications. The device powers up instantly from the internal Flash, making it suitable for applications where fast configuration is required.

Architecture

The XC3S50AN-4TQG144C features 1,584 logic cells organised into 176 configurable logic blocks (CLBs). Each CLB contains four slices, each slice containing two 4-input look-up tables (LUTs) and two flip-flops, providing flexible logic implementation. The hierarchical SelectRAM memory architecture includes 54 Kbits of block RAM and 11 Kbits of distributed RAM, totalling 55,296 bits of on-chip memory. The device also includes three 18x18 dedicated multipliers for digital signal processing acceleration.

I/O and Clock Management

The device provides 108 user I/O pins supporting a wide range of single-ended and differential signalling standards, including LVCMOS, LVTTL, HSTL, SSTL, LVDS, and RSDS. SelectIO technology allows each I/O bank to operate at 3.3V, 2.5V, 1.8V, 1.5V, or 1.2V levels. Two Digital Clock Managers (DCMs) provide precise clock management capabilities including clock skew elimination, frequency synthesis, phase shifting, and clock distribution, supporting internal logic operation up to 667 MHz and I/O switching up to 250 MHz.

Configuration and Security

The device supports multiple configuration interfaces including JTAG and the internal Flash mode. A unique Device DNA identifier is included for design authentication and IP protection. The embedded Flash also provides enhanced design security by preventing unauthorised readback of the configuration bitstream. Suspend and hibernate modes are available for power management in portable and battery-operated applications.

Packaging and Environmental

The XC3S50AN-4TQG144C is housed in a 144-pin TQFP (Thin Quad Flat Pack) package measuring 20 x 20 mm with a 0.5 mm pitch. The package is RoHS compliant (ROHS3) and REACH unaffected. Moisture Sensitivity Level is MSL 3, requiring a floor life of 168 hours after opening. The device is supplied in tray packaging.

Development Support

Supported by Xilinx ISE WebPACK and ISE Design Suite (ISE 14.7). The device is not supported by the newer Vivado toolchain, which targets 7-series and later devices. For new designs requiring nonvolatile FPGA technology with modern tool support, consider the Xilinx Spartan-7 family or other recent alternatives.

Product Status

The XC3S50AN-4TQG144C is marked as obsolete by DigiKey. Stock is limited and the device is no longer in active production. For existing designs, verify supply availability before committing to volume production.