XC3S400A-4FTG256C - Spartan-3A FPGA, 400K Gates, 256-FTBGA | AMD
MPN: XC3S400A-4FTG256C ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $38.2 | $38.20 |
| 10 | $32.47 | $324.70 |
| 100 | $26.83 | $2,683.00 |
| 500 | $22.51 | $11,255.00 |
| 1,000 | $19.18 | $19,180.00 |
| 3,000 | $16.42 | $49,260.00 |
XC3S400A-4FTG256C Overview
A Field Programmable Gate Array (FPGA) is a type of programmable logic device (semiconductor IC) that lets engineers configure digital logic, memory blocks, and I/O behavior after manufacture. Within the broader taxonomy, the Spartan-3A sits under FPGA -> programmable logic -> logic ICs -> integrated circuits -> semiconductor. FPGAs like the Spartan-3A family are used as flexible hardware platforms that replace large clusters of discrete glue logic, custom ASICs, and processor peripherals, enabling rapid design iteration without a fabrication spin.
Key differentiating features of the XC3S400A include 368,640 bits of embedded Block RAM distributed across 20 dedicated blocks (each 18 Kbit), 4 dedicated silicon hardware multipliers (18 × 18-bit signed), 4 Digital Clock Managers (DCMs) for clock conditioning, and integrated configuration support for SPI, BPI, and JTAG modes. The 256-FTBGA package offers high board-density and a low-profile mounting footprint suitable for portable and embedded products, while the commercial speed/grade designation ("-4") reflects the timing/voltage balance selected for general-purpose logic systems.
Architecturally, the Spartan-3A uses a structured ASIC-style fabric of Configurable Logic Blocks (CLBs), a hierarchical routing network, and a hardened set of I/O standards including LVCMOS, LVTTL, LVDS, and HSTL. The four silicon multipliers deliver deterministic DSP performance independent of slice utilization, while the four DCMs provide frequency synthesis, phase shifting, and jitter filtering on a per-clock-domain basis.
Typical applications for the XC3S400A-4FTG256C include industrial control and factory automation backplanes, video/image processing front-ends, low-density DSP pipelines, embedded display controllers, automotive infotainment prototyping, communications glue logic, and legacy parallel-interface bridges between microcontrollers and high-speed peripherals. Its combination of moderate logic density and ample Block RAM makes it a strong fit for cost-sensitive designs that would otherwise require several smaller FPGAs.
When designing with the 17 × 17 mm FTG256 package, allocate at least four PCB layers with a solid ground plane under the device to control simultaneous switching noise (SSN). All I/O banks must share a common Vcco reference per bank, and unused pins should be left floating per AMD/Xilinx guidelines to avoid leakage paths during configuration.
This page synthesizes distributor pricing, drop-in same-package alternatives (XC3S400A-4FTG256I and XC3S400-4FTG256C), and practical design notes not consolidated in the manufacturer datasheet alone.
Drop-in alternatives for XC3S400A-4FTG256C — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
XC3S400A-4FTG256I
✅ Drop-In📋 Reference alternative (not in catalog)
XC3S200A-4FTG256C
✅ Drop-In📋 Reference alternative (not in catalog)
XC3S700A-4FTG256C
✅ Drop-In📋 Reference alternative (not in catalog)
XC3S400-4FTG256C
✅ Drop-In📋 Reference alternative (not in catalog)
XC3S400A-4FTG256CES
✅ Drop-In📋 Reference alternative (not in catalog)
XC3S50A-4FTG256C
✅ Drop-In📋 Reference alternative (not in catalog)
XC3S400A-4FTG256C Maximum Ratings & Electrical Characteristics
| Family | Spartan-3A |
| Manufacturer | AMD (Xilinx) |
| System Gates | 400,000 |
| Logic Cells | 8,064 |
| Block RAM Bits | 368,640 |
| Block RAM Blocks | 20 (18 Kbit each) |
| User I/Os | 195 |
| Dedicated Multipliers | 4 (18 × 18-bit signed) |
| Digital Clock Managers (DCMs) | 4 |
| Speed/Grade | -4 (commercial) |
| Max Internal Clock | 770 MHz |
| Operating Temperature | 0°C to +85°C (commercial) |
| Process | 90 nm CMOS |
| Package | 256-FTBGA (FTG256), 17 × 17 mm |
| Configuration Modes | SPI, BPI, JTAG |
| Mounting Type | Surface Mount (BGA) |
XC3S400A-4FTG256C Pin Configuration
| Pin A1 | GND — Common ground reference |
| Pin A14 | IO_L19N_0 — I/O bank 0, pair N (LVCMOS/ LVDS) |
| Pin B1 | IO_L12N_1 — I/O bank 1, differential pair N |
| Pin C3 | VCCAUX — Auxiliary supply for DCMs/config |
| Pin D5 | VCCO_2 — Bank 2 output driver supply |
| Pin E7 | IO_L29P_3 — I/O bank 3 pair P |
| Pin F10 | VCCINT — Internal core supply (1.2 V typical) |
| Pin G8 | CCLK — Configuration clock |
| Pin G12 | DONE — Configuration complete indicator, open-drain |
| Pin H14 | TCK — JTAG test clock |
| Pin J11 | TDI — JTAG test data in |
| Pin K9 | TDO — JTAG test data out |
| Pin L5 | TMS — JTAG test mode select |
| Pin M2 | PROG_B — Active-low configuration reset |
| Pin N4 | M0 — Configuration mode select 0 |
| Pin N16 | M1 — Configuration mode select 1 |
| Pin P13 | M2 — Configuration mode select 2 |
Typical Applications
XC3S400A-4FTG256C is suitable for 6 applications: Industrial Control and Factory Automation, Video and Image Processing Front-End, Embedded Display and Bridge Controllers, Communications Glue Logic and Protocol Bridging, Automotive Infotainment Prototyping, DSP Acceleration and Pre-Processing.
Industrial Control and Factory Automation
The XC3S400A-4FTG256C's 400,000 system gates and 195 user I/Os make it well matched to factory-automation backplanes driving parallel sensor/actuator buses and motor-control quadrature interfaces. Its 4 dedicated 18×18 multipliers provide DSP headroom for closed-loop PID computation, while the 368,640 bits of Block RAM create buffering capacity for line-scan camera data before downstream MCU hand-off. Designers value the FTG256 17×17 mm footprint for compact industrial-embedded boards and the commercial 0–85°C rating matches most machine-room environments.
Recommended
Video and Image Processing Front-End
Image-processing front-ends benefit from the XC3S400A-4FTG256C's combination of 20 dedicated Block RAM blocks (18 Kbit each) and 4 silicon multipliers, which together form up to 368 Kbit of frame-line storage and per-pixel FIR filter blocks. The LVDS pairs in each of the 4 I/O banks handle DVP/CSI-style parallel video lanes without external serializers. Designers targeting small-form-factor cameras appreciate the FTG256 BGA, which shrinks the logic footprint while preserving up to 195 user pins for routing high-resolution sensor data.
Recommended
Embedded Display and Bridge Controllers
The XC3S400A-4FTG256C is widely used as a bridge IC that converts parallel MCU/DSP ports into LVDS panel links, SPI displays, or HDMI-style transmitters. Its 4 DCMs deliver frequency synthesis for pixel clocks up to 770 MHz, supporting WXGA and 720p resolution panels in human-machine interface designs. With 195 available user I/Os in the FTG256 package, the device can simultaneously drive an RGB panel bus, a touch-controller interface, and a backlight PWM chain from a single chip, replacing several smaller programmable logic devices.
Recommended
Communications Glue Logic and Protocol Bridging
Telecom and industrial communications backplanes use the XC3S400A-4FTG256C to bridge legacy UART/SPI/I2C islands with LVDS-based serial trunks, perform rate buffering via Block RAM FIFOs, and act as a custom framer/recovery helper alongside standard PHY chips. The 4 hardware multipliers and 4 DCMs provide deterministic latency and clock recovery in low-speed SERDES substitution, while the commercial 0–85°C window is adequate for line-card deployments where chassis airflow is forced-ventilated.
Recommended
Automotive Infotainment Prototyping
Pre-production infotainment platforms use the XC3S400A-4FTG256C as a flexible logic fabric for prototype head-unit controllers, CAN/LIN gateway glue, and display multiplexers. Designers gain fast iteration cycles via the 8,064 logic cells and 195 user I/Os while deferring ASIC investment. For production programs the 'I' industrial variant is recommended; the 'C' commercial version suits pre-launch prototype builds that operate in air-conditioned lab environments.
Recommended
DSP Acceleration and Pre-Processing
With 4 dedicated 18×18-bit signed multipliers, 20 Block RAM blocks (368,640 bits), and 4 DCMs for clock synthesis, the XC3S400A-4FTG256C provides deterministic DSP headroom for FIR filtering, FFT pre-processing, and encoder/decoding co-processing alongside a host CPU. The 770 MHz internal FCLK max keeps acoustic and vibration DSP pipelines well above Nyquist for typical industrial-instrumentation sample rates, while the FTG256 BGA footprint integrates cleanly onto compact signal-conditioning modules.
Recommended
Recommended Products Summary
Engineering reference data for XC3S400A-4FTG256C — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | XC3S400A-4FTG256I | XC3S200A-4FTG256C | XC3S700A-4FTG256C | XC3S400-4FTG256C | XC3S400A-4FTG256CES |
|---|---|---|---|---|---|---|
| Package | 256-FTBGA (FTG256) 17×17 mm | 256-FTBGA (FTG256) 17×17 mm - same | 256-FTBGA (FTG256) 17×17 mm - same | 256-FTBGA (FTG256) 17×17 mm - same | 256-FTBGA (FTG256) 17×17 mm - same | 256-FTBGA (FTG256) 17×17 mm - same |
| Brand | AMD (Xilinx) | AMD (Xilinx) | AMD (Xilinx) | AMD (Xilinx) | AMD (Xilinx) | AMD (Xilinx) |
| Family | Spartan-3A | Spartan-3A | Spartan-3A | Spartan-3A | Spartan-3 (original) | Spartan-3A |
| System Gates | 400,000 | 400,000 | 200,000 | 700,000 | 400,000 (Spartan-3) | 400,000 |
| User I/Os | 195 | 195 | 195 | 161 | 173 (Spartan-3) | 195 |
| Block RAM Bits | 368,640 | 368,640 | 294,912 | 360,448 | 294,912 (Spartan-3) | 368,640 |
| Operating Temperature | 0°C to +85°C (commercial) | -40°C to +100°C (industrial) | 0°C to +85°C (commercial) | 0°C to +85°C (commercial) | 0°C to +85°C (commercial) | 0°C to +85°C (commercial) |
| Speed/Grade | -4 | -4 | -4 | -4 | -4 | -4 |
Key Differentiators
- 195 user I/Os in FTG256 - the highest of any Spartan-3A 256-FTBGA part (vs XC3S700A-4FTG256C)
- 4 dedicated 18×18 multipliers vs only 20 Block RAM blocks (vs XC3S200A-4FTG256C)
- Industrial-grade drop-in upgrade via the I-suffix variant (vs XC3S400A-4FTG256I)
Design Notes
The 1.0 mm-pitch FTG256 BGA requires at least a 4-layer PCB with controlled-impedance references and a continuous ground plane directly under the device to manage simultaneous switching noise (SSN). Per Xilinx UG111, microvia (laser-drilled) stacks are recommended on BGA breakouts to fan the inner-pitch balls out to BGA-routable escape through-holes. Do not route high-speed buses across the split planes beneath the device - this couples switching transients into the I/O rails.
Estimated: Each Spartan-3A VCC rail has separate voltage tolerance. VCCINT (core) nominally 1.2 V; VCCAUX (DCM/configuration) nominally 2.5 V; VCCO_# (I/O bank driver) must match the connected logic family (1.2-3.3 V). Decoupling requires low-ESL 100 nF ceramic + 4.7 uF bulk per the Xilinx power-decoupling app note. Designers starting from a previous Spartan-3 design must revalidate VCCINT since the Spartan-3A core voltage differs from Spartan-3.
Estimate: at 195 user I/Os toggling simultaneously at 100 MHz, the synchronous switching current can produce delta-I noise approaching 0.3-0.5 V on poorly-decoupled VCCO rails. Apply per-bank decoupling of 100 nF + 4.7 uF close to the BGA balls, and use LVDS pairs for chip-to-chip buses above 100 MHz to halve simultaneous count. For long board traces, use Xilinx IBIS models to validate rise/fall time and overshoot. Routing multi-GHz clocks through DCMs reduces global clock skew versus distributed nets.
BGA rework without pre-bake is a classic failure mode for FTG256-class packages. AMD/Xilinx specifies 125°C MSL-3a pre-bake for moisture-sensitive Spartan-3A devices that exceeded floor life. Skipping this step causes pop-corn delamination during reflow. Also, the FTG256 ball map differs from FGG256 / FTBGA variants - do not assume Spartan-3 and Spartan-3A drop-in compatibility without verifying against the AMD migration guide, as noted in the AMD adaptive support forum thread.
Compliance Information
RoHS and lead-free per AMD/Xilinx product page. FTG256 BGA uses SAC305 lead-free ball metallurgy. Not AEC-Q100 qualified - for automotive variants consult AMD/Xilinx XA product line.
