AMD XC3S400A-4FT256I

Overview

XC3S400A-4FT256I from AMD (formerly Xilinx) is a Spartan-3A FPGA with 400,000 system gates, 8,064 logic cells, and 216 I/O pins in a 256-pin Fine-Pitch Ball Grid Array (FBGA) package. It operates at -4 speed grade (1.57 ns CLB delay), supports SelectIO™ standards up to 622 Mbps, and targets cost-sensitive industrial control and communication interface logic.

For engineers reviewing the XC3S400A-4FT256I datasheet, pinout, applications, or equivalent options, key selection criteria include I/O voltage flexibility (1.2 V to 3.3 V), embedded block RAM capacity (216 kbits), and support for DDR/DDR2 SDRAM interfaces in resource-constrained designs.

Technical Context

The XC3S400A-4FT256I implements a hierarchical FPGA architecture with configurable logic blocks (CLBs), distributed RAM, and dedicated carry logic. It integrates eight Digital Clock Managers (DCMs) supporting phase shifting, frequency synthesis, and duty cycle correction across multiple clock domains.

Configuration is performed via Master Serial mode using external PROM or JTAG boundary-scan. The device supports IEEE 1149.1 compliance and includes internal configuration monitoring with CRC error detection for bitstream integrity verification.

Key Specifications

Pinout & Package

XC3S400A-4FT256I is housed in a 256-ball fine-pitch BGA (FT256) package with 1.0 mm ball pitch, 17 mm × 17 mm body size, and thermal pad exposed on underside for enhanced heat dissipation in sustained logic operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC3S400A-4FT256I, the XC3S500E-4FT256C offers more logic but sacrifices industrial temperature rating and bitstream security, while the XC6SLX9-2TQG144C provides better power efficiency and DDR3 capability in a smaller footprint-making it suitable for next-generation cost-optimized embedded systems where Spartan-3A toolchain dependency is not mandatory.

Availability

XC3S400A-4FT256I is available at Aetrix Electronics and suitable for industrial automation, legacy system upgrades, and embedded video processing requiring stable component supply over extended production lifecycles.

Supply support for XC3S400A-4FT256I 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 maintains the Spartan FPGA product family for cost-optimized, high-volume programmable logic applications.

The Spartan-3A series was designed specifically for industrial control, communications infrastructure, and video interface applications where predictable timing, I/O flexibility, and long-term availability are critical.

FAQ

What is the maximum supported I/O standard voltage for XC3S400A-4FT256I?

XC3S400A-4FT256I supports I/O voltages from 1.2 V to 3.3 V across six independently powered I/O banks. Each bank's VCCO setting determines compatible standards-e.g., 3.3 V enables LVTTL and LVCMOS33, while 1.8 V supports SSTL18. This allows mixed-voltage interface design without level shifters. The XC3S400A-4FT256I datasheet specifies absolute maximum ratings and recommended operating conditions per bank.

Does XC3S400A-4FT256I support JTAG boundary-scan testing?

Yes, XC3S400A-4FT256I fully complies with IEEE 1149.1 (JTAG) for boundary-scan testing and in-system programming. Its TCK, TMS, TDI, and TDO pins implement standard test access port functionality, enabling automated PCB test, configuration verification, and debug access. The XC3S400A-4FT256I also supports JTAG-based partial reconfiguration in supported toolchains.

How many Digital Clock Managers (DCMs) does XC3S400A-4FT256I include?

XC3S400A-4FT256I integrates eight Digital Clock Managers (DCMs), each capable of frequency synthesis, phase shifting, and duty cycle correction. These DCMs operate independently and support clock inputs up to 248 MHz. The XC3S400A-4FT256I uses them for generating multiple synchronized clocks required in video timing, communication protocols, and motor control loops.

Is XC3S400A-4FT256I pin-compatible with other Spartan-3A devices in FT256 packaging?

XC3S400A-4FT256I shares the same 256-ball FT256 footprint with XC3S200A-4FT256I and XC3S1000A-4FT256I, but pin functions differ due to varying I/O counts and internal routing. While mechanical mounting is identical, direct substitution requires verification of I/O bank assignments, power pin locations, and configuration pin placement. The XC3S400A-4FT256I pinout must be validated against its specific package drawing before board reuse.

What configuration modes are supported by XC3S400A-4FT256I?

XC3S400A-4FT256I supports Master Serial, Slave Serial, Slave Parallel, and JTAG configuration modes. Master Serial is most common, using an external SPI PROM to load the bitstream automatically on power-up. The XC3S400A-4FT256I also permits fallback to JTAG for development and field updates, with configuration status monitored via the DONE pin.