AMD XC3S400-4PQG208I

Overview

XC3S400-4PQG208I from AMD (formerly Xilinx) is a Spartan-3 FPGA with 400,000 system gates, 241 I/O pins, and configured in a 208-pin PQFP package with Pb-free (RoHS-compliant) finish. It operates at -4 speed grade (tPD = 4.5 ns), supports SelectIO standards including LVCMOS, LVTTL, and PCI, and targets cost-sensitive embedded control and interface bridging applications.

For engineers reviewing the XC3S400-4PQG208I datasheet, pinout, applications, or equivalent options, key selection criteria include I/O count, speed grade timing compliance, package thermal profile, and compatibility with Xilinx ISE 14.7 design tools and Spartan-3 configuration PROMs.

Technical Context

The XC3S400-4PQG208I implements a hierarchical FPGA architecture with configurable logic blocks (CLBs), distributed RAM, block RAM (176 kbits), and dedicated multipliers. It uses SRAM-based configuration with external serial or parallel PROM loading via Master Serial or Slave Parallel mode.

It supports global clock routing with four dedicated clock networks, DLL-based clock deskew, and digital clock managers (DCMs) for frequency synthesis and phase alignment. Configuration is volatile and requires external non-volatile memory for power-up initialization.

Key Specifications

Pinout & Package

XC3S400-4PQG208I is housed in a 208-pin Plastic Quad Flat Pack (PQFP) with 0.5 mm pitch, 28 × 28 mm body, and exposed pad for thermal dissipation. Package meets JEDEC MS-026 standard and supports reflow soldering per IPC/JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FPGA-based interface and control applications.

Compared with XC3S400-4PQG208I, XC3S500E-4PQ208C offers greater logic capacity and I/O bandwidth in identical packaging, while XC3S200A-4VQ100C reduces size and cost at the expense of I/O count and gate resources - enabling tiered design scaling across product families.

Availability

XC3S400-4PQG208I is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and test equipment requiring stable component supply and long-term obsolescence management.

Supply support for XC3S400-4PQG208I 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 continues to support the Spartan-3 family under its adaptive computing portfolio. Xilinx pioneered FPGA technology with emphasis on programmable logic density, I/O flexibility, and design tool integration.

The Spartan-3 family was designed for cost-optimized, high-volume applications requiring reliable programmable logic with robust I/O and embedded clock management - especially in industrial control, video processing, and communications infrastructure.

FAQ

What is the maximum operating frequency supported by the XC3S400-4PQG208I?

The XC3S400-4PQG208I has a -4 speed grade with a typical combinational path delay (tPD) of 4.5 ns. Its maximum system clock frequency depends on design topology but commonly achieves 150–200 MHz for register-to-register paths using DCM-synchronized logic. The DCMs support input frequencies up to 200 MHz and generate outputs up to 320 MHz with phase alignment.

Does the XC3S400-4PQG208I require external configuration memory?

Yes, the XC3S400-4PQG208I uses volatile SRAM-based configuration and requires external non-volatile memory (e.g., XCF02S or XCF04S PROM) for automatic loading at power-up. Configuration can occur via Master Serial, Slave Parallel, or JTAG modes - all dependent on external memory or host processor initialization.

Can the XC3S400-4PQG208I operate in industrial temperature range?

Yes, the XC3S400-4PQG208I is rated for -40°C to +100°C (Industrial grade). This is confirmed by its "I" suffix and data sheet specification. Thermal design must account for PQFP package dissipation limits and ensure board-level airflow or copper pour meets junction temperature requirements under full logic utilization.

Which software tools support design and programming of the XC3S400-4PQG208I?

The XC3S400-4PQG208I is fully supported by Xilinx ISE Design Suite 14.7 - the final official release for Spartan-3 devices. It includes synthesis, place-and-route, timing analysis, and bitstream generation. Programming is performed via iMPACT or ChipScope Pro using JTAG or slave parallel interfaces.

How many differential I/O pairs does the XC3S400-4PQG208I support?

The XC3S400-4PQG208I supports up to 120 single-ended I/Os or 60 differential pairs (LVDS, RSDS, BLVDS) depending on bank voltage and termination configuration. Differential signaling requires adjacent pins within the same I/O bank and matching VCCO/VREF settings - verified in the Spartan-3 DC and Switching Characteristics datasheet.