AMD XC3S400-4PQ208C

Overview

XC3S400-4PQ208C from AMD (formerly Xilinx) is a Spartan-3 FPGA with 400,000 system gates, 241 I/O pins, and configured in a 208-pin PQFP package; it operates at -4 speed grade (4.5 ns CLB delay), supports SelectIO standards including LVCMOS, LVTTL, and PCI, and is used in industrial control logic and legacy communication interface bridging.

For engineers reviewing the XC3S400-4PQ208C datasheet, pinout, applications, or equivalent options, key selection factors include I/O voltage flexibility (3.3V/2.5V/1.8V compatible), embedded block RAM capacity (288 kbits), distributed RAM resources, and support for JTAG boundary-scan testing per IEEE 1149.1.

Technical Context

The XC3S400-4PQ208C implements a hierarchical FPGA architecture with configurable logic blocks (CLBs), dedicated multipliers, and digital clock managers (DCMs) for phase-aligned clock synthesis. It integrates 864 CLBs, 24 block RAMs (each 18 kbits), and up to 241 user I/Os with programmable slew rate and drive strength.

It supports configuration via Master Serial, Slave Serial, or JTAG modes using external PROM or processor-controlled loading. The device uses 1.2 V core voltage and 3.3 V I/O voltage by default, with internal voltage regulation for core logic stability.

Key Specifications

Pinout & Package

XC3S400-4PQ208C is housed in a 208-pin Plastic Quad Flat Pack (PQFP) with 0.5 mm pitch, 28 × 28 mm body size, and exposed thermal pad (non-electrical). Package meets JEDEC MS-026 standard and supports reflow soldering per IPC/JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FPGA-based logic implementation applications.

Compared with XC3S400-4PQ208C, the XC3S500E-4PQ208C offers headroom for future logic expansion within identical packaging, while the XC3S200A-4VQ100C trades gate count and I/O for compactness and lower unit cost-making them complementary rather than drop-in replacements.

Availability

XC3S400-4PQ208C is available at Aetrix Electronics and suitable for industrial control, legacy interface bridging, and test equipment applications requiring stable component supply across extended production lifecycles.

Supply support for XC3S400-4PQ208C 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 and markets adaptive computing platforms including FPGAs, adaptive SoCs, and AI engines.

The Spartan-3 family was designed for cost-sensitive, high-volume applications requiring reliable programmable logic with integrated clock management and flexible I/O, targeting industrial, automotive, and communications infrastructure.

FAQ

What is the maximum operating frequency supported by XC3S400-4PQ208C?

The XC3S400-4PQ208C has a -4 speed grade specifying a 4.5 ns CLB propagation delay, enabling critical path operation up to 222 MHz. Actual achievable frequency depends on design placement, routing, and clock domain constraints. The device includes four Digital Clock Managers (DCMs) capable of synthesizing higher-frequency clocks from lower-speed references, but final timing closure must be verified using Xilinx ISE tools and static timing analysis for the XC3S400-4PQ208C implementation.

Does XC3S400-4PQ208C support JTAG programming and debugging?

Yes, XC3S400-4PQ208C fully supports IEEE 1149.1 JTAG boundary-scan for configuration, debugging, and verification. Its TCK, TMS, TDI, and TDO pins enable in-system programming via Xilinx iMPACT or third-party tools. JTAG mode allows bitstream loading, readback, and device identification without requiring external configuration PROM, making XC3S400-4PQ208C suitable for development and field update scenarios.

What I/O standards are supported by XC3S400-4PQ208C?

XC3S400-4PQ208C supports 17 SelectIO standards including LVCMOS (1.2 V to 3.3 V), LVTTL, PCI, HSTL Class I/II, and SSTL2 Class I/II. Each of its 241 user I/Os can be independently assigned to a supported standard per bank, with programmable drive strength, slew rate, and pull-up/pull-down resistors. This flexibility allows XC3S400-4PQ208C to interface directly with diverse peripheral families without level-shifting components.

Can XC3S400-4PQ208C be reconfigured in-system after power-up?

Yes, XC3S400-4PQ208C supports multiple in-system configuration methods including Master Serial (via external SPI PROM), Slave Serial (host-controlled), and JTAG. The PROGRAM_B pin enables asynchronous reconfiguration, and the DONE pin signals successful load completion. This allows XC3S400-4PQ208C to be updated dynamically in deployed systems, supporting field upgrades and multi-function operation without hardware replacement.

Is there on-chip monitoring capability in XC3S400-4PQ208C?

Yes, XC3S400-4PQ208C includes a System Monitor feature with an on-chip 10-bit ADC that measures internal die temperature and supply voltages (VCCINT and VCCO). This data is accessible via dedicated configuration registers and can be read through JTAG or embedded microcontroller interfaces. The monitoring capability supports thermal management and power health diagnostics in mission-critical XC3S400-4PQ208C deployments.