AMD XC3S400-4FTG256I

Overview

XC3S400-4FTG256I from AMD (formerly Xilinx) is a Spartan-3 FPGA with 400,000 system gates, 241 I/O pins, and configured in a 256-pin Fine-Pitch Thin Quad Flatpack (FTBGA) package. It integrates up to 8,064 logic cells, 288 Kbits of block RAM, and supports LVCMOS25/LVCMOS33 I/O standards for embedded control and interface bridging in industrial automation systems.

For engineers reviewing the XC3S400-4FTG256I datasheet, pinout, applications, or equivalent options, key selection criteria include logic density, I/O voltage compatibility, configuration mode support (Master Serial, Slave SelectMAP), and thermal performance under sustained operation at -40°C to +100°C junction temperature.

Technical Context

The XC3S400-4FTG256I implements a hierarchical FPGA architecture with configurable logic blocks (CLBs), distributed RAM, and dedicated carry logic for arithmetic functions. It supports JTAG boundary-scan (IEEE 1149.1) and includes Digital Clock Managers (DCMs) for input clock multiplication, division, phase shifting, and duty-cycle correction.

Configuration is performed via external PROM or processor-controlled slave parallel mode, with internal startup sequence managing configuration memory initialization, I/O state control, and global reset assertion. The device uses 1.2 V core voltage and supports multiple I/O bank voltages (1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V) with programmable drive strength and slew rate per pin.

Key Specifications

Pinout & Package

XC3S400-4FTG256I is housed in a 256-ball Fine-Pitch Thin Ball Grid Array (FTBGA) package with 1.0 mm ball pitch, 17 × 17 array, and standard JEDEC MO-251AC footprint. Thermal pad on underside enhances heat dissipation in high-utilization designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FPGA-based logic implementation applications.

Compared with XC3S400-4FTG256I, XC3S500E-4FG320C offers greater logic capacity at the cost of board layout change, while XC6SLX45-3CSG324I introduces architectural improvements including hard IP blocks but requires full re-design and toolchain migration.

Availability

XC3S400-4FTG256I is available at Aetrix Electronics and suitable for industrial motion control, automated test equipment, medical imaging interface, and communications backplane management requiring stable component supply and long-term obsolescence planning.

Supply support for XC3S400-4FTG256I includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

AMD acquired Xilinx in 2022 and now develops and supports the legacy Spartan FPGA product families, maintaining documentation, tools, and lifecycle commitments for industrial and aerospace customers.

The Spartan-3 family was designed for cost-sensitive, high-volume applications requiring balanced logic density, I/O flexibility, and predictable timing - especially in industrial control and instrumentation where long-term availability matters.

FAQ

What is the maximum operating frequency of the XC3S400-4FTG256I?

The XC3S400-4FTG256I supports a maximum system clock frequency of 280 MHz for internal logic paths under typical conditions, as verified by Xilinx ISE timing analysis with -4 speed grade. This applies to fully constrained synchronous designs meeting setup/hold requirements; actual achievable frequency depends on routing, resource usage, and I/O timing constraints. The device's DCMs can generate internal clocks up to 320 MHz with jitter specifications defined in DS099.

Does the XC3S400-4FTG256I support JTAG programming?

Yes, the XC3S400-4FTG256I fully supports IEEE 1149.1 JTAG boundary-scan for configuration, debugging, and board-level testing. It uses TDI, TDO, TMS, and TCK pins for programming via iMPACT or Vivado Hardware Manager. JTAG also enables partial reconfiguration and real-time debug probes through ChipScope Pro when implemented in the design.

What configuration modes does the XC3S400-4FTG256I support?

The XC3S400-4FTG256I supports Master Serial (with on-chip oscillator), Slave Serial, Slave SelectMAP, and Boundary Scan (JTAG) configuration modes. Configuration bitstream can be loaded from Platform Flash PROM, microcontroller, or host processor. Mode selection is controlled by MODE pins (M2:M0), and startup behavior-including GTS and GWE assertion-is defined in DS099 Table 35.

Is the XC3S400-4FTG256I RoHS compliant?

Yes, the XC3S400-4FTG256I is RoHS compliant and lead-free, meeting EU Directive 2011/65/EU and JESD204B material restrictions. The FTBGA package uses matte tin finish on solder balls, and all internal die attach, wire bond, and mold compound materials comply with halogen-free and Pb-free requirements as documented in Xilinx PDN#0253-1.

Can the XC3S400-4FTG256I operate at 3.3 V I/O voltage?

Yes, the XC3S400-4FTG256I supports 3.3 V I/O operation in dedicated I/O banks powered by VCCO = 3.3 V. Each bank is independently configurable for LVCMOS33, LVTTL, or PCI standards. However, VCCAUX must remain at 2.5 V, and core voltage (VCCINT) is fixed at 1.2 V - mixing 3.3 V I/O with lower-core voltage requires proper level-shifting awareness in timing closure.