The XC3S1000-4FG320I is a high-performance, industrial-grade Xilinx FPGA from the Spartan-3 family, manufactured by AMD (formerly Xilinx). Designed for cost-sensitive, high-volume applications, this device combines 1,000,000 system gates with a compact 320-ball Fine-pitch Ball Grid Array (FBGA) package, making it an ideal choice for embedded control, digital signal processing, and complex logic applications.
What Is the XC3S1000-4FG320I?
The XC3S1000-4FG320I is a field-programmable gate array (FPGA) belonging to Xilinx’s Spartan-3 series. The “4” in the part number denotes the speed grade, “FG320” refers to the 320-ball FBGA package, and the “I” suffix indicates an industrial temperature range (–40°C to +100°C). It is classified under the Embedded – Complex Logic (FPGA, CPLD) product category.
This device is widely used in industrial automation, communications infrastructure, consumer electronics, and test & measurement equipment where reliable, reprogrammable logic is required in harsh operating environments.
XC3S1000-4FG320I Key Specifications
General Product Information
| Parameter |
Value |
| Manufacturer |
AMD (Xilinx) |
| Part Number |
XC3S1000-4FG320I |
| Series |
Spartan-3 |
| Product Category |
Embedded – Complex Logic (FPGA) |
| RoHS Status |
RoHS Compliant |
| Moisture Sensitivity Level (MSL) |
3 / 168 Hours |
Logic & Configuration Resources
| Resource |
Value |
| System Gates |
1,000,000 |
| Logic Cells |
17,280 |
| CLB Slices |
7,680 |
| CLB Flip-Flops |
15,360 |
| Maximum Distributed RAM (bits) |
120,000 |
| Block RAM (bits) |
432,000 |
| Total Block RAM |
432 Kb |
| DSP / Multiplier Blocks |
24 × 18×18 Multipliers |
| Number of I/Os |
391 |
| DCM (Digital Clock Manager) |
4 |
Electrical Characteristics
| Parameter |
Value |
| Supply Voltage (VCC Core) |
1.2 V |
| I/O Voltage |
1.2 V ~ 3.3 V |
| Operating Temperature Range |
–40°C to +100°C (Industrial) |
| Speed Grade |
–4 (slowest of the Spartan-3 grades) |
Package & Mechanical Data
| Parameter |
Value |
| Package Type |
FBGA (Fine-pitch Ball Grid Array) |
| Package Code |
FG320 |
| Number of Balls |
320 |
| Pitch |
1.0 mm |
| Package Dimensions |
19 mm × 19 mm |
| Height (Seated) |
1.50 mm |
| Mounting Type |
Surface Mount |
XC3S1000-4FG320I Pinout and I/O Bank Structure
The XC3S1000-4FG320I offers 391 user-configurable I/Os organized into multiple I/O banks. Each bank can be independently powered, allowing the device to interface with multiple voltage standards in the same design. The 320-ball FBGA footprint provides a relatively dense I/O count for its size while enabling compact PCB layouts.
Supported I/O Standards
| I/O Standard |
Description |
| LVTTL / LVCMOS |
3.3 V, 2.5 V, 1.8 V, 1.5 V, 1.2 V |
| SSTL2 / SSTL18 |
Stub Series Terminated Logic |
| HSTL |
High-Speed Transceiver Logic |
| PCI / PCI-X |
3.3 V PCI compatible |
| DIFF (LVDS, RSDS) |
Low-voltage differential signaling |
XC3S1000-4FG320I Architecture Overview
Configurable Logic Blocks (CLBs)
The Spartan-3 CLB architecture is built around 4-input Look-Up Tables (LUTs) arranged in slices. Each CLB contains four slices, and each slice contains two LUTs and two flip-flops. This structure allows efficient implementation of combinational and sequential logic.
Block RAM
With 432 Kbits of total block RAM, the XC3S1000-4FG320I supports on-chip data storage and buffering. Block RAMs can be configured as single-port or true dual-port memories, supporting various aspect ratios and operating in synchronous mode.
Digital Clock Managers (DCMs)
The device includes 4 DCMs that provide precise clock synthesis, clock phase shifting, and frequency synthesis. DCMs eliminate skew between clock domains and allow frequency multiplication/division without external PLL components.
Multiplier Blocks
Twenty-four dedicated 18×18 multiplier blocks accelerate DSP-intensive operations such as filtering, FFT calculations, and matrix operations. Each multiplier produces a 36-bit result and can be combined with block RAMs for efficient MAC (Multiply-Accumulate) pipelines.
Industrial Temperature Grade: What the “I” Suffix Means
The “I” suffix in XC3S1000-4FG320I signifies the industrial temperature range: –40°C to +100°C junction temperature. This makes it suitable for applications outside of standard commercial environments (0°C to +85°C).
Temperature Grade Comparison
| Suffix |
Grade |
Temperature Range |
| C |
Commercial |
0°C to +85°C |
| I |
Industrial |
–40°C to +100°C |
| Q |
Automotive |
–40°C to +125°C |
Industrial-grade devices like the XC3S1000-4FG320I undergo more rigorous screening and are rated for demanding environments such as factory automation, outdoor communications equipment, and ruggedized instrumentation.
XC3S1000-4FG320I vs. Other Spartan-3 Variants
The Spartan-3 family scales from 50K to 5M system gates. Here is how the XC3S1000 compares to adjacent family members:
Spartan-3 Family Comparison Table
| Device |
System Gates |
Logic Cells |
Block RAM (Kb) |
Multipliers |
Max I/Os |
| XC3S200 |
200,000 |
4,320 |
216 |
12 |
173 |
| XC3S400 |
400,000 |
8,064 |
288 |
16 |
264 |
| XC3S1000 |
1,000,000 |
17,280 |
432 |
24 |
391 |
| XC3S1500 |
1,500,000 |
29,952 |
576 |
32 |
487 |
| XC3S2000 |
2,000,000 |
46,080 |
720 |
40 |
565 |
The XC3S1000 sits at a sweet spot for mid-complexity designs that need more resources than the XC3S400 but do not require the higher cost of the XC3S2000 or above.
Typical Applications for the XC3S1000-4FG320I
The XC3S1000-4FG320I is well-suited for a broad range of embedded and industrial applications:
- Industrial Automation – Motor control, PLC logic expansion, safety monitoring systems
- Communications – Line cards, protocol bridging (UART, SPI, I2C, Ethernet MAC)
- Test & Measurement – Data acquisition, pattern generation, logic analysis
- Consumer Electronics – Set-top boxes, digital cameras, image processing pipelines
- Aerospace & Defense – Radiation-tolerant designs (qualified variants available), signal processing
- Embedded Processing – Soft-core processor implementations (PicoBlaze, MicroBlaze)
- DSP Applications – FIR/IIR filters, FFTs, digital down-converters using the on-chip multipliers
Programming and Configuration
Configuration Modes
The XC3S1000-4FG320I supports multiple configuration methods:
| Mode |
Description |
| Master Serial |
PROM-based serial configuration |
| Slave Serial |
Daisy-chain multi-device configuration |
| Master SPI |
SPI Flash (e.g., M25P16) |
| Master BPI |
Parallel NOR Flash |
| JTAG |
IEEE 1149.1 boundary scan and in-system programming |
| Slave Parallel |
Processor-driven parallel configuration |
Development Tools
Xilinx ISE Design Suite (ISE 14.7 is the final version supporting Spartan-3) is the primary tool for synthesizing, implementing, and generating bitstreams for this device. Third-party tools including Synplify Pro and Precision RTL Synthesis are also supported.
Ordering Information
| Part Number |
Package |
Temperature |
Speed Grade |
RoHS |
| XC3S1000-4FG320C |
FBGA-320 |
Commercial (0°C to +85°C) |
–4 |
Yes |
| XC3S1000-4FG320I |
FBGA-320 |
Industrial (–40°C to +100°C) |
–4 |
Yes |
| XC3S1000-5FG320C |
FBGA-320 |
Commercial |
–5 |
Yes |
| XC3S1000-5FG320I |
FBGA-320 |
Industrial |
–5 |
Yes |
| XC3S1000-4FGG320I |
FBGA-320 |
Industrial |
–4 |
Yes |
Note: Speed grade “–5” is faster than “–4” in Xilinx nomenclature. The XC3S1000-4FG320I is the entry-level speed grade for industrial temperature applications.
PCB Design Considerations
Decoupling and Power Supply
The XC3S1000-4FG320I requires a 1.2 V core supply (VCCINT) and separate I/O bank supplies (VCCO) ranging from 1.2 V to 3.3 V. Adequate decoupling capacitors (100 nF ceramic per supply pin, 10 µF bulk per power plane) should be placed as close to the device as possible.
PCB Stack-Up Recommendations
- Use a minimum 4-layer PCB with dedicated power and ground planes beneath the BGA
- Route high-speed I/O signals on the outer layers with controlled impedance (50 Ω single-ended, 100 Ω differential)
- Follow Xilinx UG331 (Spartan-3 User Guide) recommendations for PCB layout
BGA Soldering
The 320-ball, 1.0 mm pitch BGA is compatible with standard reflow soldering processes (SAC305 lead-free alloy recommended). X-ray inspection is advised to verify solder joint integrity under the device.
Frequently Asked Questions (FAQ)
Q: What is the difference between XC3S1000-4FG320I and XC3S1000-4FGG320I? The “FGG” variant uses Pb-free packaging that is RoHS compliant. Both are functionally identical, use the same 320-ball FBGA footprint, and are pin-compatible.
Q: Is the XC3S1000-4FG320I still in production? The Spartan-3 family is in a mature lifecycle phase. Availability depends on distributor stock. It is recommended to check current distributor inventory for lead times and pricing.
Q: Can I replace XC3S1000-4FG320I with a Spartan-6 or newer device? Spartan-6 and later families are not pin-compatible with Spartan-3. Migration requires redesign, but Xilinx provides migration guides. The XC6SLX16 or XC6SLX25 in an equivalent package are common upgrade paths.
Q: What software do I need to program the XC3S1000-4FG320I? Xilinx ISE Design Suite 14.7 (free WebPACK edition is available for Spartan-3 devices). A Xilinx USB Platform Cable or equivalent JTAG programmer is required for in-system programming.
Q: What is the maximum clock frequency of the XC3S1000-4FG320I? With the –4 speed grade, internal CLB-to-CLB routing can achieve system clock frequencies typically in the range of 50 MHz to 200 MHz depending on design complexity. The DCMs can synthesize frequencies up to 280 MHz output.
Summary
The XC3S1000-4FG320I is a proven, mid-range FPGA solution offering 1 million system gates, 17,280 logic cells, 432 Kbits of block RAM, 24 hardware multipliers, and 391 user I/Os in an industrial-temperature, 320-ball FBGA package. Its combination of logic density, DSP capability, and rugged temperature specification makes it a versatile choice for embedded, industrial, and communications designs. While the Spartan-3 family is mature, the XC3S1000-4FG320I continues to serve in production designs worldwide and remains widely available through authorized electronic component distributors.
