AMD XC3S400-4FGG456C

Overview

XC3S400-4FGG456C from AMD (formerly Xilinx) is a Spartan-3 FPGA with 400,000 system gates, 241 I/O pins, and configured in a 456-pin Fine-Pitch Ball Grid Array (FBGA) package. It operates at -4 speed grade (tPD = 4.8 ns), supports SelectIO™ standards up to 333 Mbps, and targets cost-sensitive embedded control and interface bridging applications.

For engineers reviewing the XC3S400-4FGG456C datasheet, pinout, applications, or equivalent options, key selection criteria include I/O count, speed grade timing closure, bank voltage flexibility (1.2 V/2.5 V/3.3 V), and availability of dedicated DCM clock management resources.

Technical Context

The XC3S400-4FGG456C integrates eight Digital Clock Managers (DCMs) for phase-matched clock synthesis, duty-cycle correction, and frequency multiplication/division. Its logic fabric comprises 8,064 configurable logic blocks (CLBs), each with two 4-input LUTs and flip-flops, supporting synchronous design with global and regional clock routing.

It features 720 Kbits of distributed and block RAM, supports JTAG boundary-scan (IEEE 1149.1), and implements configuration via Master Serial, Slave Serial, or SelectMAP modes using external PROM or processor-controlled loading.

Key Specifications

Pinout & Package

XC3S400-4FGG456C uses a 456-pin Fine-Pitch Ball Grid Array (FBGA) package with 2.0 mm pitch, 23 × 23 array, and thermal pad. Pin functions are organized into 12 I/O banks, each supporting selectable VCCO (1.2 V, 2.5 V, or 3.3 V) and independent VREF references.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FPGA-based interface and control applications.

Compared with XC3S400-4FGG456C, XC3S500E-4FGG456C offers gate-count headroom within identical mechanical and thermal constraints, while XC6SLX45-3CSG324C delivers architectural upgrades including hardened IP and process-derived power savings - both require evaluation of toolchain compatibility and timing closure methodology.

Availability

XC3S400-4FGG456C is available at Aetrix Electronics and suitable for industrial motion control, medical imaging front-end, and automotive camera interface applications requiring stable component supply and long-term lifecycle support.

Supply support for XC3S400-4FGG456C includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

AMD acquired Xilinx in 2022 and now develops adaptive computing platforms including FPGAs, adaptive SoCs, and AI engines for data center, embedded, and edge applications.

The Spartan-3 family was designed by Xilinx to deliver high-performance, low-cost programmable logic for high-volume embedded systems where logic density, I/O flexibility, and power efficiency are critical.

FAQ

What is the maximum operating frequency supported by the XC3S400-4FGG456C?

The XC3S400-4FGG456C has a -4 speed grade, meaning its internal logic paths support a maximum clock frequency of approximately 208 MHz under typical conditions. This value derives from the 4.8 ns propagation delay (tPD) specification and assumes proper timing closure with constrained placement and routing. Actual achievable frequency depends on design complexity, I/O standard selection, and thermal environment. The XC3S400-4FGG456C DCMs can generate higher-frequency clocks internally, but logic path timing remains bound by the -4 grade.

Does the XC3S400-4FGG456C support JTAG boundary-scan testing?

Yes, the XC3S400-4FGG456C fully complies with IEEE 1149.1 (JTAG) boundary-scan architecture. Pins TCK, TMS, TDI, and TDO are dedicated for this purpose and support device identification, interconnect testing, and in-system programming. The JTAG interface operates independently of the main configuration mode and remains functional after configuration. This capability is documented in the XC3S400-4FGG456C Configuration User Guide (UG332) and verified across production silicon.

Can the XC3S400-4FGG456C be configured using an external microcontroller?

Yes, the XC3S400-4FGG456C supports SelectMAP configuration mode, allowing an external microcontroller to load the bitstream via an 8- or 16-bit parallel bus. This requires asserting PROGRAM_B, waiting for INIT_B deassertion, then driving address and data lines synchronized to CCLK. The XC3S400-4FGG456C datasheet specifies timing requirements for setup/hold and pulse widths. This method is commonly used in field-upgradable systems where firmware controls FPGA reconfiguration.

What I/O standards are supported by the XC3S400-4FGG456C?

The XC3S400-4FGG456C supports SelectIO™ standards including LVCMOS (1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V), LVTTL, PCI, HSTL Class I/II, SSTL2 Class I/II, and differential standards LVDS, RSDS, and BLVDS. Each of its 12 I/O banks can be independently powered, enabling simultaneous use of multiple voltage standards. These capabilities are defined in the XC3S400-4FGG456C DC and Switching Characteristics datasheet (DS099).

Is bitstream encryption available for the XC3S400-4FGG456C?

Yes, the XC3S400-4FGG456C supports optional AES-128 bitstream encryption using a user-provided 128-bit key stored in on-chip non-volatile memory. When enabled, the configuration bitstream must be encrypted prior to programming, and decryption occurs transparently during startup. This feature protects intellectual property against unauthorized readback or cloning. Encryption capability is implemented in hardware and documented in the XC3S400-4FGG456C Configuration User Guide.