The XC3S50-4VQ100C is a commercial-grade Field-Programmable Gate Array (FPGA) from Xilinx’s cost-optimized Spartan-3 family, housed in a compact 100-pin Very Thin Quad Flat Pack (VTQFP) package. Designed for high-volume, cost-sensitive applications, this device delivers 50,000 system gates of programmable logic at standard (-4) speed grade performance — making it a go-to choice for embedded control, consumer electronics, and digital signal processing designs.
Whether you are prototyping a new product or building into production, the XC3S50-4VQ100C offers a proven, reliable platform backed by Xilinx’s decades of FPGA expertise. It is part of the broader Xilinx FPGA portfolio, which spans from entry-level Spartan devices to high-performance Virtex families.
What Is the XC3S50-4VQ100C?
The XC3S50-4VQ100C belongs to the Spartan-3 family — an eight-member series of FPGAs optimized for cost-sensitive, high-volume markets. This specific part number decodes as follows:
| Code Segment |
Meaning |
| XC3S |
Spartan-3 Family |
| 50 |
50,000 System Gates |
| -4 |
Speed Grade 4 (Standard Performance) |
| VQ |
100-Pin Very Thin Quad Flat Pack (VTQFP) |
| 100 |
100 Pin Count |
| C |
Commercial Temperature Range (0°C to +85°C) |
XC3S50-4VQ100C Key Specifications
Core Logic Resources
| Parameter |
Value |
| System Gates |
50,000 |
| Equivalent Logic Cells |
1,728 |
| Configurable Logic Blocks (CLBs) |
192 |
| Slices per CLB |
4 |
| Total Slices |
768 |
| Flip-Flops |
1,536 |
| Maximum Distributed RAM |
12 Kbits |
Memory & DSP Resources
| Parameter |
Value |
| Block RAM Columns |
1 |
| Block RAM Size (per block) |
18 Kbits |
| Total Block RAM |
72 Kbits |
| Dedicated Multipliers (18×18) |
4 |
| Digital Clock Managers (DCMs) |
2 |
I/O and Packaging
| Parameter |
Value |
| Package |
100-Pin VTQFP (VQ100) |
| Maximum User I/O (device-wide) |
124 |
| Available User I/O (VQ100 package) |
63 |
| I/O Standards Supported |
LVCMOS, LVTTL, SSTL, HSTL, LVDS, and more |
| Operating Voltage (VCCINT) |
1.2V |
| I/O Voltage (VCCO) |
1.2V – 3.3V (bank-configurable) |
Performance & Process Technology
| Parameter |
Value |
| Speed Grade |
-4 (Standard) |
| Maximum Clock Frequency |
Up to 630 MHz (internal routing) |
| Process Technology |
90nm |
| Operating Temperature |
0°C to +85°C (Commercial) |
XC3S50-4VQ100C Ordering Information
| Part Number |
Package |
Speed Grade |
Temperature |
| XC3S50-4VQ100C |
100-Pin VTQFP |
-4 (Standard) |
Commercial (0°C to 85°C) |
| XC3S50-4VQG100C |
100-Pin VTQFP (Pb-Free) |
-4 (Standard) |
Commercial (0°C to 85°C) |
| XC3S50-4VQG100I |
100-Pin VTQFP (Pb-Free) |
-4 (Standard) |
Industrial (–40°C to 100°C) |
| XC3S50-4TQ144C |
144-Pin TQFP |
-4 (Standard) |
Commercial (0°C to 85°C) |
Note: The “G” in part numbers like XC3S50-4VQG100C denotes a Pb-free (RoHS-compliant) package. The XC3S50-4VQ100C uses standard (non-Pb-free) packaging.
Architecture Overview: Five Functional Elements
The Spartan-3 architecture is built around five tightly integrated functional elements that work together to deliver flexible, high-performance logic:
1. Configurable Logic Blocks (CLBs)
CLBs are the primary building blocks for implementing custom logic. Each CLB contains four slices, and each slice includes two 4-input Look-Up Tables (LUTs), two flip-flops, carry logic, and dedicated routing resources. The XC3S50 provides 192 CLBs (768 slices total), enabling a wide range of sequential and combinatorial designs.
2. Input/Output Blocks (IOBs)
The ring of IOBs surrounding the CLB array supports a broad set of single-ended and differential I/O standards. In the VQ100 package, 63 user I/O pins are accessible. Each IOB supports Double Data-Rate (DDR) registers and optional Digitally Controlled Impedance (DCI) — though DCI is not available in Bank 5 of the VQ100 package.
3. Block RAM
The XC3S50 features a single column of block RAM, totaling 72 Kbits of on-chip storage. Each 18 Kbit block has a dual-port structure (ports A and B), allowing simultaneous independent read and write access — ideal for FIFOs, lookup tables, and data buffers.
4. Dedicated Multipliers
Four dedicated 18×18-bit hardware multipliers are embedded alongside the block RAM, delivering high-throughput multiplication without consuming CLB resources. This makes the XC3S50-4VQ100C suitable for lightweight DSP tasks and filter implementations.
5. Digital Clock Managers (DCMs)
Two DCMs provide flexible clock management, including frequency synthesis, phase shifting, and clock deskewing. DCMs help designers meet strict timing closure requirements across complex synchronous designs.
Configuration Modes
The XC3S50-4VQ100C supports multiple configuration modes, providing flexibility for different system architectures:
| Configuration Mode |
Description |
| Master Serial |
FPGA drives CCLK; reads from serial PROM |
| Slave Serial |
External controller supplies CCLK and data |
| Master Parallel (SelectMAP) |
FPGA drives CCLK; reads 8-bit parallel data |
| Slave Parallel (SelectMAP) |
External controller provides 8-bit parallel data |
| JTAG (Boundary Scan) |
IEEE 1149.1-compliant in-system programming |
Configuration data is stored in reprogrammable static CMOS configuration latches (CCLs), which are volatile — meaning the device must be reconfigured at power-up, typically from an external SPI or BPI Flash memory.
Supported I/O Standards
The XC3S50-4VQ100C supports a rich set of single-ended and differential I/O standards, enabling easy interfacing with a wide variety of external devices:
| Standard Type |
Examples |
| Single-Ended |
LVCMOS 3.3V / 2.5V / 1.8V / 1.5V, LVTTL, PCI |
| Stub Series Terminated Logic |
SSTL2 Class I/II, SSTL18 Class I |
| High-Speed Transceiver Logic |
HSTL Class I / III / IV |
| Differential |
LVDS, LVPECL, BLVDS, RSDS |
Typical Applications
The XC3S50-4VQ100C is well-suited for a broad range of embedded and consumer electronics applications:
- Embedded system control – GPIO expansion, bus bridging, glue logic replacement
- Communications interfaces – UART, SPI, I²C, parallel bus protocol controllers
- Digital signal processing – Simple FIR/IIR filters using dedicated multipliers and block RAM
- Motor control – PWM generation, encoder decoding, commutation logic
- Consumer electronics – Image processing front ends, display timing controllers
- Industrial automation – Custom state machines, sensor interfacing, safety logic
- Prototyping and development – Rapid design iteration before committing to an ASIC
Why Choose the XC3S50-4VQ100C?
#### Cost-Optimized Entry-Level FPGA
The Spartan-3 family was purpose-built to deliver maximum functionality at the lowest possible cost per system gate. The XC3S50-4VQ100C achieves an excellent price-to-logic ratio for volume designs where BOM cost is critical.
#### Compact 100-Pin Package
At just 100 pins in a VTQFP footprint, the device is ideal for space-constrained PCB designs. Its small body size reduces board area while still providing 63 accessible user I/Os.
#### Mature, Well-Supported Platform
As a long-standing member of the Xilinx FPGA ecosystem, the Spartan-3 family is supported by decades of design resources, application notes, reference designs, and community knowledge. Legacy designs benefit from continued availability of replacement and service stock.
#### Flexible I/O Voltage Support
Bank-configurable VCCO pins allow each I/O bank to operate at a different voltage (1.2V to 3.3V), making it straightforward to interface with both legacy 3.3V peripherals and modern 1.8V or 1.5V devices on the same board.
#### JTAG In-System Programming
Full IEEE 1149.1 JTAG boundary scan support enables in-system programming and debugging without removing the device from the board, reducing development and field-service time.
Development Tools
Xilinx (now AMD) provides comprehensive toolchain support for the XC3S50-4VQ100C:
| Tool |
Purpose |
| ISE Design Suite |
Legacy synthesis, implementation, and bitstream generation (primary tool for Spartan-3) |
| PlanAhead |
Advanced floorplanning and constraint management |
| iMPACT |
Device programming and JTAG chain configuration |
| ChipScope Pro |
On-chip logic analyzer for real-time debugging |
| CORE Generator |
IP core generation for standard functions (FIFOs, DSP, interfaces) |
The Spartan-3 family is not supported by Vivado. Designers should use ISE 14.7 (the final ISE release) for all XC3S50-4VQ100C projects.
Comparison: XC3S50 vs Other Spartan-3 Devices
| Device |
System Gates |
Logic Cells |
Block RAM |
Multipliers |
DCMs |
Max I/O |
| XC3S50 |
50K |
1,728 |
72 Kbits |
4 |
2 |
124 |
| XC3S200 |
200K |
4,320 |
216 Kbits |
12 |
4 |
173 |
| XC3S400 |
400K |
8,064 |
288 Kbits |
16 |
4 |
264 |
| XC3S1000 |
1M |
17,280 |
432 Kbits |
24 |
4 |
391 |
Compliance and Environmental Information
| Attribute |
Detail |
| RoHS Compliance |
Non-Pb-free (standard tin/lead solder) for XC3S50-4VQ100C; order XC3S50-4VQG100C for Pb-free |
| REACH Compliance |
Check AMD/Xilinx compliance portal for current status |
| MSL (Moisture Sensitivity) |
MSL 3 (per JEDEC J-STD-020) |
| Halogen Content |
Contact distributor for halogen-free status |
Frequently Asked Questions
Q: What is the difference between XC3S50-4VQ100C and XC3S50-4VQG100C? The only difference is the solder finish. The “G” variant (XC3S50-4VQG100C) uses a Pb-free (RoHS-compliant) finish, while the XC3S50-4VQ100C uses standard tin/lead solder. Both are electrically and functionally identical.
Q: Is the XC3S50-4VQ100C still in production? The Spartan-3 family has been noted as not recommended for new designs at various points in its lifecycle; however, stock continues to be available through authorized distributors. For new designs, consider evaluating the Spartan-7 or Artix-7 families for a more current FPGA platform.
Q: What configuration memory should I use with the XC3S50-4VQ100C? Xilinx Platform Flash (XCF series) or third-party SPI Flash devices compatible with the Spartan-3 bitstream size are commonly used. The XC3S50 bitstream is approximately 439 Kbits, so a 1 Mbit or larger Flash is suitable.
Q: Can I use Vivado to design with the XC3S50-4VQ100C? No. Vivado does not support Spartan-3 devices. Use Xilinx ISE 14.7, which is freely available for download from the AMD/Xilinx website and supports all Spartan-3 family members.
Q: What is the maximum user I/O available in the VQ100 package? The VQ100 package provides 63 user I/O pins for the XC3S50, compared to the device maximum of 124 user I/Os available in larger packages such as the TQ144 or PQ208.
