The XC3S50-4VQ100I is a field-programmable gate array (FPGA) from the Xilinx FPGA Spartan-3 family, manufactured by AMD (formerly Xilinx). Designed for high-volume, cost-sensitive industrial and consumer electronic applications, this device delivers reliable programmable logic performance in a compact 100-pin VTQFP package with an extended industrial temperature rating. Whether you are prototyping an embedded system, designing for industrial automation, or replacing a legacy ASIC, the XC3S50-4VQ100I offers a proven, cost-efficient solution.
What Is the XC3S50-4VQ100I?
The XC3S50-4VQ100I belongs to the eight-member Spartan-3 FPGA family from Xilinx (now AMD). The part number breaks down as follows:
| Segment |
Meaning |
| XC3S50 |
Spartan-3 family, 50K system gates |
| -4 |
Speed grade 4 (standard performance) |
| VQ100 |
100-pin Very Thin Quad Flat Pack (VTQFP) package |
| I |
Industrial temperature range (–40°C to +100°C) |
This industrial-grade variant is ideal for designs that must operate reliably across wide temperature ranges, such as factory automation equipment, embedded controllers, and outdoor instrumentation.
XC3S50-4VQ100I Key Specifications
Core Electrical and Logic Parameters
| Parameter |
Value |
| FPGA Family |
Spartan-3 |
| System Gates |
50,000 |
| Logic Cells |
1,728 |
| Process Technology |
90 nm |
| Core Supply Voltage |
1.2V |
| Maximum Clock Frequency |
630 MHz |
| Package Type |
100-Pin VTQFP (Very Thin Quad Flat Pack) |
| Temperature Range |
–40°C to +100°C (Industrial) |
| RoHS Status |
Standard (non-Pb-free; Pb-free variant uses “G” suffix) |
Memory and Logic Resources
| Resource |
XC3S50 Value |
| Configurable Logic Blocks (CLBs) |
192 |
| Flip-Flops |
1,536 |
| Block RAM |
72 Kbits (4 × 18 Kbit blocks) |
| Dedicated Multipliers (18×18-bit) |
4 |
| Digital Clock Managers (DCMs) |
2 |
| Maximum User I/Os (VQ100 package) |
63 |
I/O and Package Details
| Parameter |
Value |
| Total Pin Count |
100 |
| Maximum User I/Os |
63 |
| I/O Standards Supported |
LVTTL, LVCMOS, SSTL, HSTL, and more |
| Package Body Size |
14 mm × 14 mm |
| Pitch |
0.5 mm |
| Configuration Interface |
JTAG, Master Serial, Slave Serial, Slave Parallel |
XC3S50-4VQ100I Functional Architecture
Configurable Logic Blocks (CLBs)
The Spartan-3 CLB architecture provides flexible, efficient logic implementation. Each CLB contains four slices, and each slice includes two 4-input look-up tables (LUTs), two storage elements (registers or latches), carry logic, and arithmetic multiplexers. This structure supports a broad range of combinational and sequential logic designs.
Block RAM
The XC3S50 includes a single column of block RAM, totaling 72 Kbits of true dual-port synchronous memory. Each 18-Kbit block supports independent read and write port widths, making it suitable for FIFOs, lookup tables, and small on-chip data buffers.
Dedicated Multipliers
Four 18×18-bit dedicated hardware multipliers are embedded directly in the silicon alongside the block RAM column. These multipliers accelerate DSP, signal processing, and arithmetic-intensive functions without consuming CLB resources.
Digital Clock Managers (DCMs)
The XC3S50 includes two DCMs, derived from Xilinx’s Virtex-II platform technology. The DCMs provide clock frequency synthesis, phase shifting, and deskewing capabilities, enabling precise clock domain management in complex digital systems.
I/O Blocks (IOBs)
Each user I/O pin is controlled by a fully featured I/O block that supports both input and output paths, optional registered storage, and 3-state control. The IOBs are compatible with a wide range of single-ended and differential I/O standards. Note that DCI (Digitally Controlled Impedance) signal standards are not supported in Bank 5 when using the VQ100 package.
XC3S50-4VQ100I vs. Related Variants
Engineers selecting an FPGA for a new design often compare closely related part numbers. The table below clarifies the key differences within the XC3S50 subfamily.
| Part Number |
Speed Grade |
Package |
Temperature |
Pb-Free |
| XC3S50-4VQ100C |
-4 |
100-pin VTQFP |
Commercial (0°C to 85°C) |
No |
| XC3S50-4VQ100I |
-4 |
100-pin VTQFP |
Industrial (–40°C to 100°C) |
No |
| XC3S50-4VQG100C |
-4 |
100-pin VTQFP |
Commercial (0°C to 85°C) |
Yes |
| XC3S50-4VQG100I |
-4 |
100-pin VTQFP |
Industrial (–40°C to 100°C) |
Yes |
| XC3S50-5VQ100I |
-5 |
100-pin VTQFP |
Industrial (–40°C to 100°C) |
No |
Note: The “G” in the part number (e.g., VQG100) indicates a Pb-free (RoHS-compliant) package. If your design requires RoHS compliance, choose the XC3S50-4VQG100I instead.
Spartan-3 Family Comparison: XC3S50 in Context
The XC3S50-4VQ100I is the entry-level member of the eight-device Spartan-3 family. The table below shows how it compares to larger family members.
| Device |
System Gates |
Logic Cells |
Block RAM (Kbits) |
Multipliers |
Max I/Os |
| XC3S50 |
50K |
1,728 |
72 |
4 |
124 |
| XC3S200 |
200K |
4,320 |
216 |
12 |
173 |
| XC3S400 |
400K |
8,064 |
288 |
16 |
264 |
| XC3S1000 |
1,000K |
17,280 |
432 |
24 |
391 |
| XC3S2000 |
2,000K |
33,280 |
720 |
40 |
565 |
| XC3S5000 |
5,000K |
74,880 |
1,872 |
104 |
784 |
Configuration and Programming
The XC3S50-4VQ100I uses static CMOS configuration latches (CCLs) to store its design. Configuration is non-volatile in the sense that an external configuration memory (such as a serial SPI or Platform Flash device) holds the bitstream and reloads it on power-up. Supported configuration modes include:
- Master Serial – The FPGA drives the configuration clock and reads from an external serial PROM.
- Slave Serial – An external controller provides the configuration clock and data stream.
- Slave Parallel – Faster parallel loading controlled by an external processor or CPLD.
- JTAG (Boundary Scan) – Compliant with IEEE 1149.1 for in-circuit configuration and testing.
The Xilinx ISE Design Suite (and legacy support in Vivado) is used to synthesize, implement, and generate configuration bitstreams for Spartan-3 devices.
Typical Applications for the XC3S50-4VQ100I
Thanks to its industrial temperature rating, compact footprint, and cost-effective gate density, the XC3S50-4VQ100I is well suited for a wide variety of embedded and industrial applications:
| Application Area |
Use Case Example |
| Industrial Automation |
Motor control interfaces, sensor data acquisition |
| Embedded Systems |
Custom peripheral controllers, glue logic replacement |
| Communications |
Protocol bridging (UART, SPI, I²C, parallel bus) |
| Consumer Electronics |
Display control, set-top box logic |
| Test & Measurement |
Data capture, signal conditioning front-ends |
| Automotive (non-safety) |
In-vehicle infotainment support logic |
| ASIC Prototyping |
Logic verification before tape-out |
Why Choose the XC3S50-4VQ100I Over a Mask-Programmed ASIC?
The Spartan-3 family was specifically designed as a cost-competitive alternative to ASICs for high-volume designs. Key advantages of the XC3S50-4VQ100I over traditional ASICs include:
- Zero NRE costs – No non-recurring engineering fees for mask fabrication.
- Fast time-to-market – Design iterations take hours, not months.
- Field upgradability – Firmware can be updated in the field via JTAG or a new configuration PROM.
- Lower risk – Logic bugs can be corrected without scrapping hardware.
- Small footprint – The 100-pin VTQFP package suits space-constrained PCB layouts.
Ordering and Availability
The XC3S50-4VQ100I is an active part in the AMD (Xilinx) product portfolio and is available through major authorized distributors including Digi-Key, Avnet, and Arrow Electronics. When ordering, confirm whether your supply chain or regulatory requirements mandate the Pb-free (RoHS-compliant) variant — if so, specify the XC3S50-4VQG100I.
| Ordering Detail |
Value |
| Manufacturer |
AMD (formerly Xilinx) |
| Manufacturer Part Number |
XC3S50-4VQ100I |
| Package |
100-Pin VTQFP |
| Product Status |
Active |
| RoHS |
Non-compliant (standard Sn/Pb) |
| Pb-Free Alternative |
XC3S50-4VQG100I |
Frequently Asked Questions (FAQ)
Q: What is the difference between XC3S50-4VQ100I and XC3S50-4VQG100I?
The “G” in the part number denotes Pb-free (lead-free) packaging. Both parts are electrically identical; the only difference is the solder finish on the package leads.
Q: Is the XC3S50-4VQ100I suitable for automotive applications?
The industrial temperature range (–40°C to +100°C) covers many automotive environments. However, for safety-critical automotive designs, consider the dedicated Spartan-3 XA automotive-grade family.
Q: What design tools support the XC3S50-4VQ100I?
The Xilinx ISE Design Suite is the primary supported toolchain. Xilinx Vivado provides limited legacy support. Third-party synthesis tools such as Synplify Pro are also compatible.
Q: Can the XC3S50-4VQ100I be reprogrammed in-system?
Yes. Via the JTAG interface, the device can be reconfigured at any time without removing it from the PCB. Configuration can also be updated by replacing or reprogramming the external configuration PROM.
Q: How many I/O pins are available on the 100-pin package?
The VQ100 package provides up to 63 user-configurable I/O pins on the XC3S50 device.
