The XC3S400-4FGG320I is a high-performance, industrial-grade Field Programmable Gate Array (FPGA) from AMD Xilinx, belonging to the widely adopted Spartan-3 family. With 400,000 system gates, 221 user I/Os, and a compact 320-pin Fine-Pitch Ball Grid Array (FBGA) package, this device delivers powerful reconfigurable logic in a cost-effective solution for demanding embedded design applications.
Whether you are developing industrial control systems, digital signal processing pipelines, telecommunications infrastructure, or embedded computing platforms, the XC3S400-4FGG320I offers the flexibility and performance required for next-generation designs. As a trusted Xilinx FPGA, it builds on proven Virtex-II platform technology to set new benchmarks in programmable logic.
What Is the XC3S400-4FGG320I?
The XC3S400-4FGG320I is a member of Xilinx’s Spartan-3 FPGA family, designed specifically for high-volume, cost-sensitive applications that still require substantial logic density and I/O performance. The device is manufactured on a 90nm process technology and operates at a core supply voltage of 1.2V, making it well-suited for modern low-power digital systems.
The “I” suffix in the part number designates the Industrial temperature range, confirming operation from -40°C to +100°C — ideal for harsh environments where reliability is non-negotiable.
XC3S400-4FGG320I Key Specifications at a Glance
| Parameter |
Value |
| Part Number |
XC3S400-4FGG320I |
| Manufacturer |
AMD Xilinx |
| Series |
Spartan-3 |
| System Gates |
400,000 |
| Logic Cells |
8,064 |
| CLBs (Configurable Logic Blocks) |
896 |
| User I/O Pins |
221 |
| Total RAM Bits |
294,912 |
| Maximum Frequency |
630 MHz |
| Process Technology |
90nm |
| Core Voltage (VCC) |
1.14V – 1.26V (nominal 1.2V) |
| Package |
320-Pin FBGA (19×19mm) |
| Mounting Type |
Surface Mount (SMD) |
| Operating Temperature |
-40°C to +100°C (Industrial) |
| Part Status |
Active |
XC3S400-4FGG320I Package Information
Understanding the 320-Pin FBGA Package
The FGG320 package designation refers to a Fine-Pitch Ball Grid Array with 320 solder balls arranged in a 19×19mm body. This compact BGA footprint provides superior signal integrity compared to leaded packages, making it ideal for dense PCB designs where board space is at a premium.
| Package Attribute |
Detail |
| Package Type |
FBGA (Fine-Pitch Ball Grid Array) |
| Pin Count |
320 |
| Body Size |
19mm × 19mm |
| Mounting Style |
Surface Mount (SMT) |
| Lead Finish |
Pb-Free (G suffix) / Standard options |
Note: The “GG” in FGG320 denotes the Pb-free (RoHS compliant) variant of the package. This ensures compatibility with lead-free assembly processes and global environmental compliance regulations.
XC3S400-4FGG320I Logic Architecture and Resources
Configurable Logic Blocks (CLBs)
The Spartan-3 architecture organizes its logic fabric into Configurable Logic Blocks (CLBs). Each CLB contains four slices, and each slice contains two 4-input Look-Up Tables (LUTs) and two flip-flops, enabling highly efficient implementation of both combinatorial and sequential digital logic.
| Resource |
XC3S400-4FGG320I |
| CLBs |
896 |
| Logic Cells |
8,064 |
| Flip-Flops |
8,064 |
| 4-Input LUTs |
8,064 |
| Maximum System Gates |
400,000 |
Block RAM (BRAM)
The XC3S400-4FGG320I integrates dedicated block RAM totaling 294,912 bits (approximately 36KB). This embedded memory is organized as 18Kbit dual-port RAM blocks, suitable for FIFOs, data buffers, lookup tables, and small embedded memories without consuming any CLB resources.
| Memory Resource |
Value |
| Total RAM Bits |
294,912 |
| Block RAM Organization |
18Kbit dual-port blocks |
| RAM Columns |
Dedicated (separate from CLB) |
Digital Clock Managers (DCMs)
The Spartan-3 family includes Digital Clock Managers (DCMs) that provide clock multiplication, division, phase shifting, and duty-cycle correction. The XC3S400 device provides multiple DCMs, enabling clean, flexible clock distribution across the entire FPGA fabric without relying on external PLL components.
Dedicated Multipliers
Each block RAM column in the Spartan-3 architecture is paired with an 18×18-bit dedicated hardware multiplier, enabling high-throughput DSP operations. This makes the XC3S400-4FGG320I particularly well-suited for signal processing applications requiring efficient multiply-accumulate (MAC) operations.
XC3S400-4FGG320I I/O Capabilities and Electrical Standards
User I/O Count
With 221 user I/O pins available in the 320-FBGA package, the XC3S400-4FGG320I provides substantial connectivity for interfacing to external devices, buses, sensors, and communication interfaces.
Supported I/O Standards
The Spartan-3 I/O banks support a rich set of both single-ended and differential signaling standards, ensuring compatibility with a wide range of system-level interfaces:
| I/O Standard Category |
Supported Standards |
| Single-Ended |
LVTTL, LVCMOS 3.3V/2.5V/1.8V/1.5V, PCI, GTL, HSTL, SSTL |
| Differential |
LVDS, BLVDS, LVPECL, Differential HSTL, Differential SSTL |
| High-Speed |
Up to 630 MHz toggle rate |
XC3S400-4FGG320I Configuration and Programming
Configuration Modes
The XC3S400-4FGG320I supports five standard configuration modes, providing design flexibility for both prototyping and production deployment:
| Configuration Mode |
Description |
| Master Parallel |
FPGA drives configuration bus; reads from parallel flash |
| Slave Parallel |
External controller drives parallel config bus |
| Master Serial |
FPGA reads bitstream from serial PROM |
| Slave Serial |
External controller provides serial bitstream |
| JTAG |
In-circuit configuration and debug via IEEE 1149.1 boundary scan |
Configuration Storage
Configuration data is stored in robust, reprogrammable static CMOS Configuration Latches (CCLs). Before power-on, the bitstream resides in external non-volatile memory (PROM, Flash, or equivalent). On power-up, the FPGA automatically loads the configuration, enabling true plug-and-play operation in embedded systems.
Operating Conditions and Electrical Characteristics
Absolute Maximum and Recommended Ratings
| Parameter |
Min |
Typical |
Max |
Unit |
| Core Supply Voltage (VCCINT) |
1.14 |
1.20 |
1.26 |
V |
| I/O Supply Voltage (VCCO) |
– |
3.3 / 2.5 / 1.8 / 1.5 |
– |
V |
| Operating Temperature (Industrial) |
-40 |
+25 |
+100 |
°C |
| Maximum Toggle Frequency |
– |
– |
630 |
MHz |
Speed Grade
The “-4” in the part number indicates the speed grade of this device. In Xilinx Spartan-3 nomenclature, higher negative speed grade numbers represent faster performance. The -4 grade represents an industrial-rated, performance-optimized variant capable of supporting designs up to 630 MHz.
XC3S400-4FGG320I Industrial Temperature Grade Explained
The “I” suffix confirms this part is tested and guaranteed for operation across the full Industrial temperature range: -40°C to +100°C. This makes the XC3S400-4FGG320I the preferred choice for:
- Automotive electronics and in-vehicle systems
- Industrial automation and motor control
- Military and aerospace-adjacent applications
- Outdoor telecommunications equipment
- Medical devices with extended environmental exposure
- Energy and power management systems
Commercial-grade (-40°C to +85°C) variants are also available; however, the industrial-grade XC3S400-4FGG320I is recommended wherever long-term reliability in thermally challenging environments is required.
Typical Application Areas for the XC3S400-4FGG320I
The XC3S400-4FGG320I is a versatile FPGA suitable for a broad range of end applications:
| Application Domain |
Use Case Example |
| Industrial Automation |
Motor drive control, PLC logic, sensor fusion |
| Communications |
Protocol bridging, data framing, line card logic |
| Medical Equipment |
Image acquisition, signal filtering, device control |
| Consumer Electronics |
Display controllers, audio processing |
| Embedded Computing |
Custom processor cores, co-processing |
| Test & Measurement |
Data acquisition, waveform generation |
| Automotive |
Body control modules, driver assistance logic |
Ordering Information and Part Number Decoder
Understanding the XC3S400-4FGG320I part number helps identify the exact variant required for your design:
| Field |
Value |
Meaning |
| XC |
XC |
Xilinx Commercial Product |
| 3S |
3S |
Spartan-3 Family |
| 400 |
400 |
400K System Gates |
| -4 |
-4 |
Speed Grade (-4 = faster) |
| FGG |
FGG |
Fine-Pitch BGA, Pb-Free |
| 320 |
320 |
320 Pins |
| I |
I |
Industrial Temp (-40°C to +100°C) |
Related Part Numbers and Alternatives
| Part Number |
Gates |
Package |
Temp Grade |
| XC3S400-4FGG320I |
400K |
320-FBGA |
Industrial |
| XC3S400-4FGG320C |
400K |
320-FBGA |
Commercial |
| XC3S400-4FGG456I |
400K |
456-FBGA |
Industrial |
| XC3S400-4PQ208I |
400K |
208-PQFP |
Industrial |
| XC3S1000-4FGG320I |
1M |
320-FBGA |
Industrial |
Why Choose the Spartan-3 XC3S400-4FGG320I?
The XC3S400-4FGG320I delivers a compelling combination of features that make it stand out in the cost-optimized FPGA market:
- Proven 90nm technology — mature, well-characterized process node with extensive tool support
- Superior ASIC alternative — eliminates high NRE costs and lengthy development cycles of mask-programmed ASICs
- Field re-programmability — design upgrades via bitstream update, no hardware replacement needed
- Rich ecosystem — full support in Xilinx ISE Design Suite and compatible with third-party tools
- Industrial reliability — extended temperature operation with guaranteed performance across the full range
- High logic density — 8,064 logic cells and 896 CLBs in a compact 19×19mm BGA footprint
- Embedded memory — 294,912 bits of block RAM reduces need for external memory devices
- Flexible clocking — integrated DCMs enable multi-clock domain designs without external PLLs
XC3S400-4FGG320I Design Tool Support
The XC3S400-4FGG320I is fully supported by the Xilinx ISE Design Suite, which provides:
- Synthesis and implementation tools (XST, MAP, PAR)
- Timing analysis and constraint management
- iMPACT programmer for JTAG configuration
- ChipScope Pro for in-system logic debugging
- Simulation support via ModelSim/ISim
The device is also compatible with third-party EDA tools from Synopsys, Mentor Graphics, and Cadence for customers with existing design flows.
Frequently Asked Questions About the XC3S400-4FGG320I
What is the difference between XC3S400-4FGG320I and XC3S400-4FGG320C?
The only difference is the temperature grade. The “I” variant is rated for -40°C to +100°C (Industrial), while the “C” variant is rated for 0°C to +85°C (Commercial). All logic, I/O, speed, and package specifications are otherwise identical.
Is the XC3S400-4FGG320I RoHS compliant?
Yes. The “G” in the FGG package designator confirms this part uses a Pb-free (lead-free) ball finish, compliant with RoHS environmental directives.
What configuration memory is compatible with the XC3S400-4FGG320I?
Xilinx Platform Flash PROMs (XCF series) and standard SPI/parallel NOR Flash devices are compatible for storing the FPGA bitstream. The device supports all five standard Spartan-3 configuration modes.
What is the maximum user I/O available in the 320-FBGA package?
The XC3S400-4FGG320I provides 221 user I/O pins in the 320-ball FBGA package, which is the maximum available for the XC3S400 device in this package.
Conclusion
The XC3S400-4FGG320I is a robust, industrial-grade Spartan-3 FPGA from AMD Xilinx that combines 400,000 system gates, 221 user I/Os, 294,912 bits of embedded RAM, and a compact 320-pin FBGA package — all rated for industrial temperature operation from -40°C to +100°C. Its mature 90nm architecture, rich I/O standard support, and comprehensive design tool ecosystem make it a reliable choice for engineers designing complex digital systems in demanding environments.
With active part status, proven field deployments, and a clear upgrade path within the Xilinx FPGA portfolio, the XC3S400-4FGG320I remains a preferred selection for industrial, communications, medical, and embedded computing applications where dependable reconfigurable logic is essential.
