The XC3S400-4FG456C is a high-performance, cost-effective Field Programmable Gate Array (FPGA) from AMD Xilinx’s Spartan-3 family. Designed for high-volume, logic-intensive applications, this device delivers a compelling combination of programmable logic density, embedded memory, and dedicated DSP resources — all in a compact 456-pin Fine-pitch Ball Grid Array (FBGA) package. Whether you are prototyping a new embedded system or deploying a production-grade design, the XC3S400-4FG456C is a proven, reliable choice.
What Is the XC3S400-4FG456C?
The XC3S400-4FG456C belongs to AMD Xilinx’s Spartan-3 FPGA series, one of the most widely adopted Xilinx FPGA product lines in industrial and consumer electronics. The “400” in the part number refers to approximately 400,000 system gates, while “4” indicates the speed grade (-4, the fastest available in this family), and “FG456C” specifies the 456-ball Fine-pitch BGA package with commercial temperature grade.
This device is manufactured on a proven 90nm process technology, offering a strong balance between logic capacity, power consumption, and cost efficiency.
XC3S400-4FG456C Key Specifications
| Parameter |
Value |
| Manufacturer |
AMD (Xilinx) |
| Series |
Spartan-3 |
| Part Number |
XC3S400-4FG456C |
| Logic Cells |
8,064 |
| System Gates |
~400,000 |
| CLB Slices |
3,584 |
| Distributed RAM |
56 Kb |
| Block RAM |
288 Kb (16 blocks × 18 Kb) |
| Multipliers (18×18) |
16 |
| DCMs (Digital Clock Managers) |
4 |
| Maximum User I/O |
264 |
| Speed Grade |
-4 (Fastest) |
| Package |
FG456 (Fine-pitch BGA) |
| Package Pins |
456 |
| Operating Voltage (VCCINT) |
1.2 V |
| Operating Temperature |
0°C to +85°C (Commercial) |
| Process Technology |
90 nm |
XC3S400-4FG456C Pin and Package Details
Package Overview
| Package Attribute |
Detail |
| Package Type |
Fine-pitch Ball Grid Array (FBGA) |
| Ball Count |
456 |
| Body Size |
23 mm × 23 mm |
| Ball Pitch |
1.0 mm |
| Height (max) |
2.47 mm |
| RoHS Compliant |
Yes |
| Lead-Free |
Yes |
The 456-pin FBGA package provides a high pin count in a relatively small PCB footprint, making the XC3S400-4FG456C well-suited for compact, high-density board designs. The 1.0 mm ball pitch is compatible with standard PCB manufacturing processes available at most contract electronics manufacturers.
XC3S400-4FG456C Logic Architecture
Configurable Logic Blocks (CLBs)
The XC3S400-4FG456C contains 3,584 CLB slices, each consisting of two 4-input Look-Up Tables (LUTs) and two storage elements (flip-flops or latches). This architecture enables designers to implement a wide variety of combinational and sequential logic functions efficiently.
Each CLB slice also includes dedicated carry logic for fast arithmetic operations, making the device suitable for ALU implementations, counters, and state machines.
Embedded Block RAM
The device provides 16 block RAM tiles, each 18 Kb in size, for a total of 288 Kb of embedded block RAM. These BRAMs can be configured as:
| RAM Configuration |
Width |
Depth |
| 16K × 1 |
1 bit |
16,384 |
| 8K × 2 |
2 bits |
8,192 |
| 4K × 4 |
4 bits |
4,096 |
| 2K × 9 |
9 bits |
2,048 |
| 1K × 18 |
18 bits |
1,024 |
| 512 × 36 |
36 bits |
512 |
These BRAMs are true dual-port memories, supporting simultaneous read and write operations on both ports — ideal for FIFOs, lookup tables, and packet buffering.
Dedicated Multiplier Blocks
The XC3S400-4FG456C includes 16 dedicated 18×18-bit hardware multipliers, providing substantial DSP throughput without consuming CLB logic resources. These multipliers are essential for signal processing, filtering, and arithmetic-intensive applications.
Digital Clock Managers (DCMs)
Four Digital Clock Managers provide flexible, on-chip clock management including:
- Clock frequency synthesis and multiplication
- Clock phase shifting (fine and coarse)
- Clock deskewing (eliminates clock distribution delay)
- Frequency division
DCMs allow designers to derive multiple clocks from a single input reference, simplifying board-level clocking and reducing BOM cost.
XC3S400-4FG456C I/O Capabilities
I/O Summary
| I/O Parameter |
Value |
| Maximum User I/O Pins |
264 |
| I/O Standards Supported |
LVTTL, LVCMOS (1.2V–3.3V), SSTL, HSTL, LVDS, PCI, GTL+ |
| Input Voltage (max) |
3.465 V |
| Output Drive Strength |
Programmable (2 mA to 24 mA) |
| On-chip Termination |
Programmable pull-up/pull-down |
Supported I/O Standards
| Standard |
Type |
Voltage |
| LVCMOS 3.3V |
Single-ended |
3.3 V |
| LVCMOS 2.5V |
Single-ended |
2.5 V |
| LVCMOS 1.8V |
Single-ended |
1.8 V |
| LVCMOS 1.5V |
Single-ended |
1.5 V |
| LVTTL |
Single-ended |
3.3 V |
| LVDS |
Differential |
2.5 V |
| SSTL2 Class I/II |
Single-ended |
2.5 V |
| HSTL Class I |
Single-ended |
1.5 V |
| PCI 3.3V |
Single-ended |
3.3 V |
Power Supply Requirements
| Supply Rail |
Voltage |
Purpose |
| VCCINT |
1.2 V |
Core logic power |
| VCCAUX |
2.5 V |
Auxiliary circuits, DCMs |
| VCCO |
1.2 V – 3.3 V |
I/O bank supply (per bank) |
The separate VCCO supply per I/O bank allows different banks to operate at different voltage levels simultaneously, enabling direct interfacing to mixed-voltage systems without level translators.
XC3S400-4FG456C Configuration Modes
| Mode |
Interface |
Description |
| Master Serial |
SPI Flash |
FPGA drives SPI clock; simplest configuration setup |
| Slave Serial |
External MCU/FPGA |
Serial bitstream from external host |
| Master Parallel (SelectMAP) |
Parallel Flash/MCU |
8-bit or 16-bit parallel bus |
| Slave Parallel (SelectMAP) |
External MCU |
Fastest configuration speed |
| JTAG (Boundary Scan) |
IEEE 1149.1 |
Debug, test, and in-system programming |
The device supports configuration from low-cost SPI serial flash devices, reducing BOM cost in production systems. The XC3S400-4FG456C uses SRAM-based configuration memory, meaning the design must be reloaded from external non-volatile memory at power-up.
XC3S400-4FG456C vs. Other Spartan-3 Devices
| Device |
Logic Cells |
Block RAM |
Multipliers |
Max I/O |
Speed Grade |
| XC3S200-4FT256C |
4,320 |
216 Kb |
12 |
173 |
-4 |
| XC3S400-4FG456C |
8,064 |
288 Kb |
16 |
264 |
-4 |
| XC3S1000-4FG456C |
17,280 |
432 Kb |
24 |
391 |
-4 |
| XC3S1500-4FG456C |
29,952 |
576 Kb |
32 |
391 |
-4 |
The XC3S400-4FG456C occupies the mid-range of the Spartan-3 family — offering significantly more logic than entry-level devices while remaining cost-effective compared to higher-density alternatives.
Typical Applications for the XC3S400-4FG456C
| Application Area |
Use Case Examples |
| Industrial Control |
Motor control, PLC co-processing, sensor fusion |
| Communications |
Protocol bridges (UART, SPI, I2C, CAN), line cards |
| Consumer Electronics |
Display controllers, image processing |
| Medical Devices |
Signal acquisition, data logging, patient monitoring |
| Automotive |
ADAS prototyping, CAN/LIN interfaces |
| Test & Measurement |
Logic analyzers, protocol analyzers |
| Military / Aerospace |
Data buses (MIL-STD-1553), signal processing |
| Embedded Systems |
Custom processor cores, co-processors |
Design Tools and Development Support
Software Toolchain
The XC3S400-4FG456C is fully supported by AMD Xilinx ISE Design Suite 14.7, the primary design environment for Spartan-3 devices. Key features include XST synthesis, ISim simulation, IMPACT programming, ChipScope Pro in-system logic analysis, and PlanAhead for advanced floorplanning.
Note: AMD Xilinx Vivado does not support Spartan-3 devices. Designers starting new projects may wish to evaluate Spartan-6 or Artix-7 for a forward-compatible migration path.
Available IP Cores
A wide library of pre-verified soft IP cores is compatible with this device, including MicroBlaze soft processor, Ethernet MAC (10/100), DDR/DDR2 memory controllers, PCI interface controllers, and a full suite of UART, SPI, I2C, and GPIO peripherals.
Ordering Information
| Attribute |
Detail |
| Part Number |
XC3S400-4FG456C |
| Manufacturer |
AMD (Xilinx) |
| Package |
FG456 FBGA |
| Temperature Grade |
Commercial (0°C to +85°C) |
| RoHS Status |
RoHS Compliant |
| Lead Finish |
Lead-Free (Pb-Free) |
Part Number Decoder
| Field |
Value |
Meaning |
| XC3S |
XC3S |
Spartan-3 Family |
| 400 |
400 |
~400K system gates |
| -4 |
4 |
Speed grade (-4 = fastest) |
| FG |
FG |
Fine-pitch BGA package |
| 456 |
456 |
456 pins |
| C |
C |
Commercial temperature (0°C to +85°C) |
Frequently Asked Questions About the XC3S400-4FG456C
What is the difference between XC3S400-4FG456C and XC3S400-5FG456C?
The only difference is the speed grade. The -4 suffix indicates a faster device with tighter timing specifications compared to the -5 (slower) variant. The -4 speed grade is preferred for designs with demanding timing constraints.
Is the XC3S400-4FG456C RoHS compliant?
Yes. The XC3S400-4FG456C is fully RoHS compliant and manufactured using lead-free solder ball materials.
Can the XC3S400-4FG456C be used with Vivado?
No. AMD Xilinx Vivado does not support Spartan-3 devices. The XC3S400-4FG456C requires ISE Design Suite 14.7, which remains available for download from the AMD Xilinx website.
What flash memory is compatible with the XC3S400-4FG456C?
The XC3S400-4FG456C is compatible with Xilinx Platform Flash (XCF) devices and a wide range of third-party SPI serial flash devices from manufacturers such as Micron, Spansion, and Winbond. Xilinx provides a detailed compatibility list in the Spartan-3 Configuration User Guide.
Conclusion
The XC3S400-4FG456C is a versatile, reliable, and cost-effective FPGA solution for mid-range logic designs. With 8,064 logic cells, 288 Kb of block RAM, 16 dedicated multipliers, 4 Digital Clock Managers, and 264 user I/O pins in a compact 456-ball FBGA package, it provides ample resources for embedded control, communications, and digital signal processing applications. Its -4 speed grade ensures maximum timing headroom, and its broad I/O standard support simplifies system integration across a wide range of voltage domains.
