The XC3S4000-4FG900I is a high-density, industrial-grade Field-Programmable Gate Array (FPGA) from Xilinx’s Spartan-3 family. Featuring 4 million system gates, 62,208 logic cells, and a robust 900-pin FBGA package, the XC3S4000-4FG900I is engineered for demanding digital logic designs across industrial, telecommunications, and embedded systems applications. Whether you are a hardware engineer looking for a reliable programmable logic solution or a procurement specialist sourcing components, this guide covers everything you need to know about the XC3S4000-4FG900I.

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What Is the XC3S4000-4FG900I?

The XC3S4000-4FG900I is a member of the Xilinx FPGA Spartan-3 family — a product line designed specifically for cost-sensitive, high-volume applications that demand flexible and reprogrammable digital logic. Built on 90nm process technology and operating at a core voltage of 1.2V, this device delivers a compelling balance of performance, density, and power efficiency.

The “I” suffix in XC3S4000-4FG900I denotes the industrial temperature grade, meaning it is rated to operate across a junction temperature range of -40°C to +100°C. This makes it suitable for harsh environments where standard commercial-grade FPGAs would fail.

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XC3S4000-4FG900I Key Specifications

The table below summarizes the essential technical parameters of the XC3S4000-4FG900I:

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XC3S4000-4FG900I Package & Pinout Overview

The XC3S4000-4FG900I uses a 900-pin Fine-Pitch Ball Grid Array (FBGA) package with a footprint of 31mm × 31mm. BGA packaging provides a very high I/O density in a compact area, making the XC3S4000-4FG900I suitable for space-constrained PCB designs.

Design Tip: When routing the XC3S4000-4FG900I on a PCB, use a minimum of 4-layer stackup to properly distribute power planes and decouple the core and I/O banks. Refer to the Xilinx PCB design guidelines for recommended decoupling capacitor placement near VCC and GND balls.

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XC3S4000-4FG900I Logic Architecture

Configurable Logic Blocks (CLBs)

The XC3S4000-4FG900I contains 6,912 CLBs, each consisting of four slices. Every slice includes lookup tables (LUTs), flip-flops, and carry logic, enabling the implementation of arithmetic functions, registers, and complex combinational logic with high efficiency.

Distributed RAM and Block RAM

The FPGA offers both distributed RAM (implemented within CLBs) and dedicated block RAM modules, contributing to a total on-chip storage capacity of 1,769,472 bits (approximately 1.69 Mb). This is well-suited for buffering, FIFO implementations, and on-chip data storage.

Digital Clock Manager (DCM)

The XC3S4000-4FG900I incorporates Digital Clock Manager (DCM) blocks, which provide:

• Clock frequency synthesis and multiplication
• Phase shifting for timing alignment
• Clock deskewing to reduce propagation delays
• Duty-cycle correction

These features are critical for designs requiring precise timing relationships between multiple clock domains.

Multipliers and DSP Resources

Dedicated 18×18 hardware multiplier blocks are embedded throughout the fabric. These accelerate DSP operations such as FIR filtering, FFT computation, and signal correlation — all without consuming general-purpose CLB resources.

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XC3S4000-4FG900I I/O Capabilities

Supported I/O Standards

The XC3S4000-4FG900I supports a wide range of single-ended and differential I/O standards, making it highly versatile for interfacing with memory, processors, and other peripherals.

I/O Bank Structure

User I/O pins are organized into multiple I/O banks, each independently configurable for different voltage levels (VCCO). This allows the XC3S4000-4FG900I to interface simultaneously with multiple voltage domains on the same board without external level-shifting circuitry.

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XC3S4000-4FG900I Power Requirements

Proper power supply design is essential for reliable FPGA operation. The XC3S4000-4FG900I requires multiple supply rails:

Note: VCCINT and VCCO are independently supplied. Ensure your power sequencing follows Xilinx’s recommended startup sequence to avoid latch-up conditions.

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XC3S4000-4FG900I vs. Similar Xilinx Spartan-3 Devices

Understanding how the XC3S4000-4FG900I compares to similar devices helps engineers select the right component for their design requirements.

The XC3S4000-4FG900I occupies the sweet spot between the smaller XC3S2000 and the larger XC3S5000, offering maximum I/O count in the 4M-gate density tier. Compared to the XC3S4000-4FG676I, the 900-pin variant provides 144 additional user I/O pins, which is advantageous in designs requiring extensive external connectivity.

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Typical Applications for the XC3S4000-4FG900I

The XC3S4000-4FG900I is deployed across a wide range of industries and system types:

Industrial Automation and Control

The industrial temperature rating (-40°C to +100°C TJ) makes the XC3S4000-4FG900I an excellent choice for PLCs, motor controllers, and factory automation equipment where operating environments are demanding and reliable long-term operation is critical.

Telecommunications Equipment

With its high I/O count, fast operating frequency, and support for LVDS differential signaling, the XC3S4000-4FG900I is well-suited to line cards, protocol converters, and signal processing modules in telecommunications infrastructure.

Embedded Systems and SoC Prototyping

Hardware engineers use the XC3S4000-4FG900I for prototyping custom SoC (System on Chip) designs, implementing soft-core processors (such as Xilinx MicroBlaze), and verifying RTL designs before committing to ASIC tape-out.

Broadband Access and Home Networking

The Spartan-3 family was designed with broadband and networking applications in mind. The XC3S4000-4FG900I can implement MAC layers, DSP pipelines, and custom network interface logic at a cost-effective price point.

Digital Video and Display Processing

The combination of large on-chip RAM, DSP multipliers, and high I/O bandwidth makes the XC3S4000-4FG900I a strong fit for video frame buffering, real-time image processing, and display controller designs.

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Programming and Design Tools for XC3S4000-4FG900I

The XC3S4000-4FG900I is supported by Xilinx’s legacy ISE Design Suite, which remains the primary toolchain for Spartan-3 devices. Key tools include:

Important: The Xilinx Vivado Design Suite does not support Spartan-3 devices. Designers must use ISE 14.7 (the final ISE release) for XC3S4000-4FG900I development.

Configuration Methods

The XC3S4000-4FG900I supports multiple configuration modes:

• Master Serial – using an external SPI or serial flash device
• Slave Serial – controlled by an external processor or CPLD
• JTAG – for in-circuit programming and debugging
• Master Parallel – for parallel flash memory configuration

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Ordering Information and Part Number Decoder

Understanding the XC3S4000-4FG900I part number helps identify key attributes at a glance:

The commercial temperature variant of this device is the XC3S4000-4FG900C (rated 0°C to +85°C TJ). For designs requiring faster timing performance, the XC3S4000-5FG900I uses the same package but at a higher speed grade.

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Frequently Asked Questions (FAQ)

Q: Is the XC3S4000-4FG900I still in production? A: Yes, the XC3S4000-4FG900I is currently listed as Active status by AMD (Xilinx). It remains available through authorized distributors such as Digi-Key and Mouser.

Q: What is the difference between XC3S4000-4FG900I and XC3S4000-4FG900C? A: The only difference is the temperature grade. The “-I” suffix denotes industrial grade (-40°C to +100°C TJ), while the “-C” suffix denotes commercial grade (0°C to +85°C TJ). All other electrical specifications are identical.

Q: Can I use Vivado for XC3S4000-4FG900I? A: No. Spartan-3 devices are not supported by Vivado. You must use Xilinx ISE Design Suite (version 14.7 is recommended).

Q: What flash memory is compatible with the XC3S4000-4FG900I for configuration? A: Xilinx Platform Flash devices (XCF series) are directly compatible. Third-party SPI flash memories such as Micron N25Q and Spansion S25FL families are also widely used.

Q: Is the XC3S4000-4FG900I RoHS compliant? A: No, the XC3S4000-4FG900I is not RoHS compliant. If RoHS compliance is required, verify with your distributor whether a compliant variant is available, or consider an alternative Spartan family device with a green/RoHS designation.

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Summary

The XC3S4000-4FG900I is a proven, industrial-grade Xilinx Spartan-3 FPGA offering 4 million system gates, 62,208 logic cells, 633 user I/O pins, and a 900-pin FBGA package. Its extended industrial temperature range, large on-chip RAM, and broad I/O standard support make it a dependable choice for industrial automation, telecommunications, embedded systems, and digital video applications. Supported by the mature Xilinx ISE toolchain, the XC3S4000-4FG900I continues to be a go-to device for engineers who need high-density programmable logic in a cost-efficient, robust package.