The XC3S4000-4FG1156I is a high-density, industrial-grade field-programmable gate array (FPGA) from the Xilinx Spartan-3 family, now under AMD. Designed for demanding embedded system applications requiring large logic capacity, robust I/O, and extended temperature operation, this device delivers exceptional value in a fine-pitch BGA package. Whether you are targeting communications infrastructure, industrial control, or signal processing, the XC3S4000-4FG1156I offers the programmable logic resources and reliability your design demands.

For a broader selection of programmable logic solutions, explore our full range of Xilinx FPGA products.

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What Is the XC3S4000-4FG1156I?

The XC3S4000-4FG1156I belongs to the Xilinx Spartan-3 generation — a cost-optimized FPGA family engineered for high-volume production environments. The part number breaks down as follows:

• XC3S4000 – Spartan-3 series, 4 million gate equivalent density
• -4 – Speed grade (–4 is the slowest/most conservative of the commercial grades, optimized for power and yield)
• FG1156 – Fine-pitch Ball Grid Array (FBGA), 1156 balls
• I – Industrial temperature range (–40°C to +100°C)

This device is specifically optimized for applications where wide I/O bus widths, large block RAM, and industrial temperature compliance are critical requirements.

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XC3S4000-4FG1156I Key Specifications

General Device Parameters

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I/O and Electrical Characteristics

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Memory and Logic Resources

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Package & Ordering Information

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XC3S4000-4FG1156I vs. Similar Spartan-3 Variants

Understanding how the XC3S4000-4FG1156I compares to related variants helps engineers select the right device for their design constraints.

Key distinction: The FG1156 package provides the highest I/O count (712 pins) in the XC3S4000 family, making it ideal for wide data bus, parallel interface, and high pin-count applications. The “I” suffix guarantees industrial temperature range operation down to –40°C.

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Functional Description

## CLB (Configurable Logic Block) Architecture

The Spartan-3 CLB consists of slices, each containing two 4-input LUTs (look-up tables), two flip-flops, and dedicated carry and arithmetic logic. The XC3S4000 provides 27,648 slices, enabling complex digital logic, state machines, arithmetic pipelines, and custom protocol engines.

Each LUT can function as:

• A 4-input logic function
• A 16×1-bit distributed RAM
• A 16-bit shift register (SRL16)

## Block RAM (BRAM)

The device integrates 104 dual-port 18 Kbit block RAMs (totaling 1,872 Kbits). Each block RAM supports:

• True dual-port operation
• Configurable aspect ratios (16K×1 to 512×36)
• Optional output pipeline registers
• First-word fall-through (FWFT) FIFO mode

This makes the XC3S4000-4FG1156I well-suited for packet buffering, FIFO implementation, dual-port memory, and embedded lookup tables.

## Dedicated Multipliers

104 dedicated 18×18-bit signed/unsigned multipliers are embedded in the device, enabling high-throughput DSP operations without consuming CLB resources. These are ideal for FIR filters, FFT engines, and matrix arithmetic.

## Digital Clock Manager (DCM)

Four DCMs provide:

• Clock multiplication and division
• Phase shifting (fine-grained)
• Clock skew minimization
• Spread-spectrum clock support
• DFS (Digital Frequency Synthesizer) operation

The DCMs allow the designer to derive multiple synchronized clock domains from a single input reference, critical for high-speed interface design.

## I/O Architecture

The FG1156 package exposes 712 user I/O pins across 8 configurable I/O banks. Each bank supports an independently selectable I/O standard and VCCO voltage. This multi-standard I/O capability allows the XC3S4000-4FG1156I to interface directly with a broad range of memory, processor, and peripheral devices without level-shift circuitry.

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Industrial Temperature Range: Why It Matters

The “I” suffix designates operation across the –40°C to +100°C junction temperature range. This is critical for:

• Outdoor and harsh-environment deployments – Telecom base stations, industrial automation, and military-adjacent systems
• Automotive electronics – Test and diagnostic equipment requiring wide thermal tolerance
• Data center and server applications – High-ambient-temperature rack equipment
• Embedded systems with passive cooling – Where junction temperatures can climb significantly above ambient

Commercial-grade FPGAs (suffix “C”) are only rated to 0°C–85°C junction temperature. For designs without active cooling guarantees or deployed in uncontrolled environments, the industrial-grade XC3S4000-4FG1156I provides the necessary reliability margin.

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Typical Applications

The XC3S4000-4FG1156I is widely deployed in applications that require a combination of large logic capacity, high I/O count, embedded memory, and DSP resources:

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Design Tools and Support

## Xilinx ISE Design Suite

The XC3S4000-4FG1156I is supported by Xilinx ISE Design Suite (up to ISE 14.7, the final release for Spartan-3). The design flow includes:

• Project Navigator – RTL design entry and management
• XST (Xilinx Synthesis Technology) – HDL synthesis
• PlanAhead – Floorplanning and physical constraint management
• iMPACT – Device programming and boundary scan
• ChipScope Pro – In-system logic analysis and debug

## Supported HDLs and IP Cores

• VHDL, Verilog, SystemVerilog (synthesis subset)
• Xilinx IP Core Generator (FIFO, memory controllers, DSP blocks, PCI cores)
• Third-party IP (MicroBlaze softcore processor, OpenCores IPs)

## Configuration Interfaces

The device supports multiple configuration modes:

• Master/Slave Serial – SPI Flash or daisy-chain configuration
• Master/Slave SelectMAP (Parallel) – High-speed configuration via 8/16/32-bit bus
• JTAG – Boundary scan and direct programming (IEEE 1149.1)
• Master/Slave SPI – Using Xilinx Platform Flash or third-party SPI devices

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PCB Design Guidelines

## Power Supply Requirements

Each power rail should be decoupled with a combination of bulk capacitors (10 µF–100 µF) and high-frequency ceramic capacitors (100 nF) placed close to each supply pin.

## Thermal Management

The XC3S4000 at full utilization dissipates significant power. For the FG1156 package, designers should:

• Calculate power consumption using the Xilinx Power Estimator (XPE) tool
• Place a heatsink for high-utilization designs in elevated ambient temperatures
• Ensure sufficient PCB copper pours under the BGA for thermal dissipation
• Use the ICCINT/ICCO current specifications from the datasheet for power supply sizing

## Signal Integrity for High Pin-Count BGA

With a 1,156-ball, 1.0 mm pitch package, PCB layout requires careful attention to:

• Escape routing – Use via-in-pad or dog-bone escape patterns for inner ball rows
• Controlled impedance – 50 Ω single-ended, 100 Ω differential for high-speed signals
• Power delivery – Minimize VCC plane impedance with a dedicated power delivery network (PDN)

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Frequently Asked Questions (FAQ)

Q: What is the difference between XC3S4000-4FG1156I and XC3S4000-4FG676I? A: Both have identical logic resources (62,208 cells), but the FG1156 package provides 712 I/O pins versus 489 for the FG676. The FG1156 is a larger 35×35 mm body. Choose FG1156 when your design requires more than 489 user I/O.

Q: Is the XC3S4000-4FG1156I still in production? A: The Spartan-3 family has reached end-of-life (EOL) status. AMD/Xilinx recommends migrating to newer families such as Spartan-6 or Spartan-7 for new designs. However, the XC3S4000-4FG1156I remains available through authorized distributors and component brokers for legacy support and production continuity.

Q: Can I use Vivado Design Suite with this device? A: No. Vivado only supports 7-Series and newer Xilinx devices. The XC3S4000-4FG1156I requires ISE Design Suite 14.7, which remains freely downloadable from the AMD/Xilinx website.

Q: What configuration memory is compatible with this FPGA? A: Xilinx Platform Flash (XCF) series devices and third-party SPI NOR flash devices (e.g., Micron, Winbond, Macronix) compatible with Xilinx’s SPI configuration scheme. The configuration bitstream size for the XC3S4000 is approximately 11.9 Mbit.

Q: What is the configuration bitstream size? A: The XC3S4000 configuration bitstream is approximately 11,954,160 bits (~1.49 MB). Select a configuration device with at least this capacity.

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Compliance and Certifications

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Summary

The XC3S4000-4FG1156I is a proven, high-density industrial FPGA that delivers 62,208 logic cells, 712 I/O pins, 1,872 Kbits of block RAM, and 104 dedicated DSP multipliers in a robust 1156-ball BGA package. Its industrial temperature rating (–40°C to +100°C) makes it suitable for the most demanding deployment environments. While the Spartan-3 series is mature technology, it remains a reliable and cost-effective choice for legacy system support, production continuity, and applications where its feature set is well-matched to design requirements.

For new designs, consider evaluating AMD Xilinx Spartan-7 or Artix-7 FPGAs for improved performance, lower power, and continued tool support.