The XC3S400-4FG456I is a high-performance, cost-efficient Field-Programmable Gate Array (FPGA) from the Xilinx Spartan-3 family. Manufactured under AMD Xilinx, this industrial-grade device delivers 400,000 system gates, 8,064 logic cells, and a 456-pin Fine-Pitch Ball Grid Array (FBGA) package — making it an ideal choice for embedded systems, digital signal processing, telecommunications, and industrial automation applications. Whether you are designing consumer electronics or rugged industrial systems, the XC3S400-4FG456I provides exceptional programmable logic performance at a competitive price point.
What Is the XC3S400-4FG456I?
The XC3S400-4FG456I is a member of the Xilinx FPGA Spartan-3 product family. It expands on the success of earlier Spartan-IIE devices by increasing logic resources, internal RAM capacity, I/O count, and overall performance. Built on 90nm process technology and featuring voltage operation at 1.2V, it sets a new standard in the programmable logic space by combining Virtex-II platform-derived enhancements with a price-to-performance ratio suitable for high-volume production designs.
The suffix breakdown of the part number is important for procurement:
- XC3S400 → Spartan-3 family, 400K system gates
- 4 → Speed grade (-4)
- FG456 → 456-pin Fine-Pitch BGA package
- I → Industrial temperature range (–40°C to +100°C)
XC3S400-4FG456I Key Specifications
General Specifications
| Parameter |
Value |
| Manufacturer |
AMD Xilinx (formerly Xilinx Inc.) |
| Part Number |
XC3S400-4FG456I |
| Series |
Spartan-3 |
| Product Category |
Embedded – FPGAs (Field Programmable Gate Array) |
| Part Status |
Active |
| RoHS Status |
Non-RoHS Compliant |
| Published / Available Since |
2009 |
Logic and Memory Resources
| Resource |
Specification |
| System Gates |
400,000 |
| Logic Cells |
8,064 |
| CLB Array |
Configurable Logic Blocks (CLBs) with 4-input LUTs |
| Block RAM |
288 Kb (built-in) |
| Dedicated Multipliers |
16 |
| Digital Clock Managers (DCMs) |
4 |
Electrical and Physical Specifications
| Parameter |
Specification |
| Core Voltage (VCCINT) |
1.2V |
| I/O Standards |
LVCMOS, LVTTL, SSTL, HSTL, PCI, LVDS, and more |
| Maximum User I/O Pins |
264 |
| Package Type |
FBGA (Fine-Pitch Ball Grid Array) |
| Pin Count |
456 |
| Package Dimensions |
23mm × 23mm |
| Process Technology |
90nm |
| Maximum Frequency |
630 MHz |
| Operating Temperature |
–40°C to +100°C (Industrial Grade) |
| Moisture Sensitivity Level (MSL) |
3 |
Clock Management
| Feature |
Details |
| Digital Clock Managers (DCMs) |
4 |
| Clock Inputs |
Multiple dedicated global clock inputs |
| DLL / PLL Support |
Yes – via DCM with phase shifting, frequency synthesis, and duty cycle correction |
XC3S400-4FG456I Package and Ordering Information
Package Details
| Attribute |
Detail |
| Package Code |
FG456 |
| Package Type |
FBGA – Fine-Pitch Ball Grid Array |
| Ball Pitch |
1.0mm |
| Package Size |
23mm × 23mm |
| Total Pins |
456 |
| User I/O Pins |
264 |
Ordering Information
| Part Number |
Speed Grade |
Package |
Temperature Grade |
| XC3S400-4FG456C |
-4 |
456 FBGA |
Commercial (0°C to 85°C) |
| XC3S400-4FG456I |
-4 |
456 FBGA |
Industrial (–40°C to +100°C) |
| XC3S400-5FG456C |
-5 |
456 FBGA |
Commercial |
Note: The “I” suffix in XC3S400-4FG456I denotes the Industrial temperature grade, making it suitable for harsh environments.
XC3S400-4FG456I Architecture Overview
How Spartan-3 FPGA Logic Works
The Spartan-3 architecture is organized around five fundamental programmable functional elements:
1. Configurable Logic Blocks (CLBs) CLBs are the core of the FPGA fabric. Each CLB contains four slices, and each slice contains two 4-input Look-Up Tables (LUTs), two storage elements (flip-flops or latches), and dedicated carry logic. These are interconnected through a flexible routing matrix.
2. Input/Output Blocks (IOBs) The XC3S400-4FG456I provides 264 user-configurable I/O pins, organized into multiple I/O banks. Each IOB supports a wide range of single-ended and differential signaling standards, including LVDS, SSTL2, SSTL3, HSTL, and PCI.
3. Block RAM Embedded 18Kb dual-port synchronous Block RAM modules are distributed throughout the device. With a total of 288 Kb of Block RAM, the XC3S400-4FG456I supports high-throughput data buffering and FIFO implementations.
4. Dedicated Multipliers The device includes 16 dedicated 18×18-bit hardware multipliers for accelerating DSP, FIR filter, and arithmetic-intensive workloads without consuming CLB logic.
5. Digital Clock Managers (DCMs) Four on-chip DCMs provide clock synthesis, phase shifting, frequency division, and duty-cycle correction. This eliminates the need for external clock conditioning components.
Applications of the XC3S400-4FG456I
The XC3S400-4FG456I is engineered for demanding, real-world applications across multiple industries. Its industrial temperature range and generous logic resources make it a reliable choice in the following fields:
Industrial and Embedded Control
| Application |
Use Case |
| Motor Control |
PWM generation, encoder feedback, multi-axis coordination |
| Machine Vision |
Image preprocessing, edge detection pipeline |
| PLC Replacement |
Custom logic controllers for factory automation |
| Industrial Communication |
Implementation of Modbus, CANbus, or EtherCAT controllers |
Communications and Networking
| Application |
Use Case |
| Protocol Bridging |
SPI, I2C, UART, Ethernet MAC |
| Data Framing |
High-speed serial data alignment and framing |
| Broadband Access |
DSL and cable modem front-end processing |
Digital Signal Processing (DSP)
| Application |
Use Case |
| FIR/IIR Filters |
Leverages 16 dedicated multipliers |
| FFT Computation |
Parallel processing via CLB arrays |
| Audio Processing |
Multi-channel mixing and decoding |
| Radar/Sonar |
Signal acquisition and processing pipelines |
Other Key Application Areas
- Medical imaging and diagnostics equipment
- Aerospace data acquisition and telemetry
- Automotive monitoring and control systems
- Consumer electronics: digital TV, projectors, home networking
Why Choose XC3S400-4FG456I Over Other FPGAs?
XC3S400-4FG456I vs. Competing Spartan-3 Variants
| Part Number |
Gates |
I/O Pins |
Package |
Temp Grade |
| XC3S200-4FG320I |
200K |
173 |
320 FBGA |
Industrial |
| XC3S400-4FG456I |
400K |
264 |
456 FBGA |
Industrial |
| XC3S1000-4FG456I |
1M |
391 |
456 FBGA |
Industrial |
| XC3S1500-4FG456I |
1.5M |
391 |
456 FBGA |
Industrial |
The XC3S400-4FG456I occupies a sweet spot in the Spartan-3 family — offering substantially more logic and I/O than the XC3S200 while maintaining a lower cost compared to higher-density variants. For most medium-complexity embedded designs, it provides the right balance.
Advantages vs. Mask-Programmed ASICs
- No non-recurring engineering (NRE) costs
- Faster time-to-market with field-reconfigurable logic
- Design changes achievable through bitstream reprogramming
- Reduced risk in low-to-medium volume production runs
Configuration and Programming
Supported Configuration Modes
The XC3S400-4FG456I supports multiple configuration modes to suit different system architectures:
| Mode |
Description |
| Master Serial |
FPGA reads configuration data from a serial Flash (SPI) |
| Slave Serial |
External controller streams bitstream into FPGA |
| Master Parallel (SelectMAP) |
Byte-wide parallel configuration for fast startup |
| Slave Parallel (SelectMAP) |
Host processor drives configuration over 8-bit bus |
| JTAG |
IEEE 1149.1 boundary scan for in-system programming |
Compatible Design Tools
| Tool |
Description |
| Xilinx ISE Design Suite |
Primary synthesis and implementation tool for Spartan-3 |
| Xilinx Vivado |
Supported via legacy IP integration |
| ModelSim / Questa |
RTL simulation support |
| ISIM |
Included functional and timing simulation within ISE |
The Xilinx ISE Design Suite (version 14.7) is the recommended toolchain for designing with the XC3S400-4FG456I. Supports both VHDL and Verilog RTL design entry.
Absolute Maximum Ratings
| Parameter |
Rating |
| Storage Temperature |
–65°C to +150°C |
| Maximum VCCINT |
1.32V |
| Maximum VCCO |
4.0V |
| Maximum VCCAUX |
3.135V |
| ESD Protection |
HBM 2000V, MM 200V (typical) |
⚠️ Operating beyond absolute maximum ratings may permanently damage the device. Always refer to the official AMD Xilinx datasheet (DS099) for full ratings.
Frequently Asked Questions (FAQ)
What does the “I” suffix mean in XC3S400-4FG456I?
The “I” designates the Industrial temperature grade, guaranteeing operation from –40°C to +100°C. This makes the part suitable for harsh environment deployments such as industrial automation, automotive testing, and outdoor telecom equipment.
What is the difference between XC3S400-4FG456C and XC3S400-4FG456I?
The only difference is the operating temperature range. The “C” variant (Commercial) is rated from 0°C to 85°C, while the “I” variant (Industrial) is rated from –40°C to +100°C. All electrical and logic specifications are otherwise identical.
Is the XC3S400-4FG456I RoHS compliant?
No. The XC3S400-4FG456I is non-RoHS compliant. Engineers working on RoHS-restricted designs should consider the XC3S400-4FGG456I (automotive/AEC-Q100 grade) or contact AMD Xilinx for compliant alternatives.
What configuration memory is recommended for the XC3S400-4FG456I?
Xilinx Platform Flash devices (XCFxxP or XCFxxS series) and compatible SPI-NOR Flash chips are recommended for serial and parallel configuration. For JTAG-based programming, the Xilinx Platform Cable USB II is the standard tool.
What logic density does 400K gates correspond to?
The 400K system gate count is equivalent to approximately 8,064 logic cells (CLB slices). System gate counts include logic cells, routing resources, and memory, and serve as a comparative figure across device families.
Product Summary
| Field |
Details |
| Part Number |
XC3S400-4FG456I |
| Manufacturer |
AMD Xilinx |
| Family |
Spartan-3 |
| Gates |
400,000 |
| Logic Cells |
8,064 |
| Max Frequency |
630 MHz |
| I/O Pins |
264 (User) |
| Block RAM |
288 Kb |
| Multipliers |
16 × 18×18-bit |
| DCMs |
4 |
| Package |
456-Pin FBGA |
| Supply Voltage |
1.2V (VCCINT) |
| Temperature Range |
–40°C to +100°C (Industrial) |
| Process Node |
90nm |
| RoHS |
Non-Compliant |
| Configuration Interface |
JTAG, Serial, Parallel (SelectMAP) |
| Design Tool |
Xilinx ISE 14.7 |
The XC3S400-4FG456I continues to be a reliable, proven programmable logic solution for engineers who need cost-effective industrial-grade FPGA performance. Its combination of 264 user I/O, dedicated DSP multipliers, and industrial temperature support makes it a competitive option for a broad spectrum of embedded and control applications.
