Xilinx Spartan-3A FPGA

What are the Features and Advantages of Xilinx Spartan-3A FPGA?

Xilinx is gradually driving several optimized platforms for optimal design solutions. The Xilinx Spartan 3A FPGA is the most affordable I/O optimized FPGAs. The Spartan 3A belongs to the Field-Programmable Gate Arrays (FPGAs).

Xilinx Spartan-3A FPGA – What is it?

Xilinx Spartan- 3A FPGA provides an efficient solution to the design problem. This holds especially in high-volume I/O-intensive electronic applications. Also, it features densities within the range of 50,000 to 1.4 million system gates. Spartan- 3A FPGAs are an extended Spartan- 3A family. The Spartan-3A family includes the Spartan-3AN and the Spartan-3A DSP FPGAs. Also, the Spartan-3E family existed before the Spartan-3A family.

The Spartan-3A family has more improvements than Spartan-3 and Spartan-3E FPGAs. The new features included in Spartan-3A reduce configuration costs. Also, these features enhance system performance. The family enhancements with the 90mm process technology help to provide more functionality. Also, this helps Spartan-3A to deliver more bandwidth for each dollar than ever before. Therefore, this development has set the new development in the programmable logic industry.

Due to the extremely low cost of Spartan- 3A FPGA, it is ideal for several consumer electronics. Spartan- 3A FPGA is ideal for digital television equipment and broadband access. Also, the Spartan- 3A FPGA is a better option to mask programmed ASICs. It is low-cost and allows field design upgrades, unlike conventional ASICs.


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Features of Xilinx Spartan- 3A FPGA

  • Spartan- 3A FPGA comes with great features which include:
  • High-performance and low-cost solutions for cost-sensitive applications.
  • More flexible logic resources
  • About eight Digital Clock Managers
  • Eight global clock networks and eight more clocks for each half device
  • Configuration interface to suit industry-standard PROMs
  • Affordable QFP and BGA packaging
  • Hibernate modes minimize system power
  • Flexible power management

The Architectural and Configuration Overview of Xilinx Spartan- 3A FPGA

Spartan- 3A FPGA architectural design features five basic programmable functional elements. These elements include:

  • Digital Clock Manager (DCM)Blocks

DCM blocks offer digital solutions for multiplying, phase-shifting, delaying, and dividing clock signals.

  • Block RAM

This features data storage in 18-Kbit dual-port blocks.

  • Configurable Logic Blocks

Also known as CLBs, it contains Look-Up Tables (LUTs). LUTs use logic plus storage elements that serve as latches or flip-flops.

  • Multiplier Blocks

These calculate the product of two 18-bit binary numbers

  • Input/Output Blocks

These blocks regulate data flow between the internal logic of the device and the I/O pins. IOBs support various signal standards like high-performance differential standards.


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What is the Configuration of Spartan-3A FPGA?

Spartan-3A FPGA is simply programmed. This is by entering configuration data into reprogrammable CMOS configuration latches. Also, the CCLs control all routing resources and functional elements. Also, the configuration data of the FPGA is externally stored in a non-volatile medium like PROM. In addition, any of the seven modes are specifically used to write the configuration data to the FPGA. The modes include:

  • Serial Peripheral Interface from an SPI serial Flash
  • Slave Parallel from a processor
  • Master Serial from a Xilinx PROM
  • Boundary Scan from a system tester or processor
  • Slave Serial from a processor
  • Byte Peripheral Interface (BPI)

Also, Spartan-3A FPGA enables two or more FPGA configuration bitstreams to save up in a BPI neither parallel NOR flash. It decides the type of configuration to load and when to load it. Furthermore, each Spartan-3A FPGA has a distinct DNA identifier. This is ideal for anti-cloning designs and tracking purposes.

The I/O Capabilities of Spartan-3A FPGA

The Spartan-3A FPGA interface supports several differential and single-ended standards. Also, there are different user I/Os and differential I/O pairs for each package combination. In addition, this FPGA supports these single-ended standards:

  • SSTL I and II at 3.3V, 2.5V, and 1.8V
  • 3V low-voltage TTL
  • 3V PCI at 66 MHz or 33 MHz
  • Low-voltage CMOS at 1.8V, 3.3V, and more
  • HSTL I, II, and III at 1.8V and 1.5V

Also, Spartan-3A FPGA supports these differential standards:

  • Differential SSTL I/O and HSTL
  • Bus LVDS I/O at 2.5v
  • LVPECL inputs at 2.5V or 3.3V
  • LVDS, PPDS I/O at 3.3V or 2.5V


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Advantages of Xilinx Spartan-3A FPGA

Spartan-3A FPGA features some advantages. These make it a better solution than other FPGAs.

Low-cost features

Spartan-3A FPGA features five different dives with system gates that range from 50k to 1.4M gates. Also, the I/Os ranges from 108 to 502 I/Os. This FPGA supports about 576 Kbits of fast-block RAM and about 176 Kbits of distributed RAM. Also, some multipliers that enable efficient DSP implementation. The multipliers allow DCMs for clock management functions.

Great configuration capabilities

Spartan-3A FPGA has improved Multi-Boot capability with a timer for guaranteed configuration. With this, it is easy to recover from configuration errors. Also, field upgradeability can be easily improved.

First 90nm FPGA electronic serial numbering in the industry

Importantly, every FPGA features a permanent distinct Device DNA serial number. This helps to protect software and hardware IP. Also, it helps to track system ID, production serial numbers, and production registrations. Users have the flexibility to implement cost algorithms for security solutions.

Dynamic input delay

Choosing delay length for both combinatorial and registered inputs helps to adjust the timing relationship between data and clock. Also, you can change the combinatorial input delay through the interconnect. Therefore, the dynamic input delay is beneficial to source-synchronous.

Support for I/O standards

Spartan-3A FPGA is ideal for display devices that support PPDS and TMDs standards. Also, this FPGA offers the biggest support for I/O standards. Furthermore, it supports 26 differential and single-ended standards. These include SSTL3 Class I & II, TMDS, and PPDs. Also, it supports pre-engineered interface solutions like PCI Express, I2C, and more.

Versatile power-management modes

Spartan-3A FPGA features a Suspend mode that helps to preserve power. Therefore, the power of this mode is comparable to quiescent current. Also, this FPGA features a system-level synchronization and quick wake-up mechanism.


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Features of the Extended Spartan-3A FPGA Family

High performance and low-cost logic solution

The extended Spartan-3A family of FPGAs features a logic solution for cost-sensitive and high-end applications. Also, this FPGA utilizes fewer standard components and enhances system reliability.

Leading connectivity platform

This FPGA has multi-standard SelectIO™ interface pins that support popular and new signaling standards. Also, it features about 519 I/O pins. In addition, there is a selectable output drive that is about 24mA for each pin. Therefore, the extended Spartan-3A family enhances Double Data Rate (DDR).

Dedicated resources for digital signal processing applications

The extended Spartan-3A FPGA family features an 18-bit by 18-bit multiplier.

Ranked SelectRam memory architecture

There is about 2.2 Mb of fast block RAM in the Spartan-3A family. Also, there are about 373 Kb of distributed RAM. Therefore, external DDR/DDR2 SDRAM provides support for about 400 Mb/s.

Clock management with about eight Digital Clock Managers (DCMs)

The extended Spartan-3A family features high-resolution phase shifting. Also, it has a frequency range of 5MHz to >320 MHz.

Applications of Spartan-3A FPGA

The Spartan-3A FPGA is ideal for use in a wide range of applications. Also, this FPGA includes several features which make them great for high-performance applications like:

  • Home networking
  • Digital television equipment
  • Broadband access
  • Display/projection
  • Computer systems

Types of Pins on Spartan-3A FPGA

There are several pins on the Spartan-3A FPGA. Also, these pins connect within the component packages in a special way. In addition, there are about 12 different types of pins on the Spartan-3A FPGA. However, the majority of these pins are user-defined I/O pins.

I/O pin

The I/O pin is a general-purpose user pin. You can pair most pins to create differential I/Os.


This is a dual-purpose pin ideal for use in some configuration modes. It is always available as a user I/O. Also, a dual pin will act as an I/O pin if not used during configuration.


This is a general-purpose pin. The input pin features no differential termination resistor or output structure.


The dedicated configuration pin is fully powered by VCCAUX. Each package features two dedicated configuration pins.


The VCCO pin transmits power to the output buffers within the I/O bank. Therefore, this pin creates the input threshold voltage for I/O standards.


There are four dedicated JTAG pins for each device. Also, JTAG pins aren’t available as a user- I/O pin. VCCAUX powers these pins.


The type of package used determines the number of VCCINT pins. All VCCINT pins must connect to +1.2V.


The GND is the dedicated ground pin. The type of package used determines the GND pins. However, all GND pins must remain connected.


These are the Control and status pins. SUSPEND, which is powered by VCCAUX, is a dedicated pin.


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Package Pins by Type

Every package features three different voltage supply inputs. These inputs are VCCO, VCCINT, and VCCAUX. Furthermore, the numbers of pins for these functions are different in terms of package. Also, most package pins are input or I/O pins. But, the type of device and the available package will determine the characteristics and numbers of these I/O.

In addition, not all I/O banks support all I/O standards. Also, the right and left banks provide support for output drive current than the bottom and top banks.

Power Management Solutions in Spartan-3A FPGA

Some applications need the lowest system cost while some require the lowest standby power. The Spartan-3A FPGA features low-power options. This FPGA features “Hibernate.” This is a power management option that enables all FPGA login turns off to save power. Hibernate requires that FPGA reconfigures before getting back to normal operation.

Also, the Spartan-3A FPGA features a power management feature known as Suspend mode.  This mode minimizes the power consumption of the FPGA while it reserves the configuration data of FPGA. Importantly, the Suspend mode reserves all data and provides quick wake-up times. On the other hand, Hibernate saves power.

Features and Benefits of the Suspend Mode

  • This mode retains FPGA configuration data and the current state of the application in FPGA.
  • Also, every user-I/O pin features an individual control that specifies how the pin acts during this mode
  • This mode reduces quiescent current by 40%. Also, active current reduces significantly.
  • Furthermore, the AWAKE pin specifies the current Suspend mode status. When SUSPEND is enabled, AWAKE becomes automatically dedicated.
  • Quick programmable wake-up time from Suspend mode.

Entering and Exiting Suspend Mode

How to enter Suspend mode

When FPGA enables in the configuration bitstream, it can enter the Suspend mode. In addition, the FPGA will power up and configure irrespective of the value used in the SUSPEND pin. However, this happens when power is instantly applied to the system. Immediately the FPGA is well-enabled through the bitstream, it enters SUSPEND mode. Also, if Bitstream doesn’t enable Suspend, the SUSPEND input won’t have any effect. Therefore, the AWAKE pin will serve as a general-purpose I/O.

All unnecessary FPGA functions shut down when the FPGA is in Suspend mode. Therefore, this helps to reduce power dissipation. During Suspend Mode, the FPGA reserves all configuration data and application state. Also, all FPGA interconnects and inputs shut down. Also, every bidirectional I/O pin or output pin assumes its suspend mode.

When the FPGA is in Suspend mode, the AWAKE pin becomes low. Furthermore, the DONE pin stays High since the FPGA still retains its configuration data.

How to Exit Suspend Mode

Exiting suspend mode in a powered system can happen in two different ways:

  • Halt the PROG_B input Low and reset the FPGA and make the FPGA reprogram
  • Exit Suspend mode by driving the Suspend input Low.

All interconnects and inputs are automatically re-enables when Suspend becomes Low. All Flip-flops set or reset if inputs and interconnects are enabled in the bitstream. Also, the flip-flops aren’t globally reset or set. This retains the application state of FPGA before entering Suspend mode.

Two user-programmable timers define when to re-enable FPGA outputs when AWAKE becomes High. Also, these timers define when to release the write-protect lock from all writable clock elements. You can also program the wake-up timing clock.


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Defining the I/O Behavior in Suspend Mode

To specify the behavior of every programmable pin differently than the default, use a SUSPEND Constraint.

Single-ended I/O standards

Every output in the FPGA application that utilizes a single-ended I/O standard can be separately programmed for one of the behaviors of Suspend mode. However, there is a default behavior in Suspend mode. In addition, this behavior specifies that the pin has to feature high impedance during Suspend mode. Therefore, this mode features some output behavior options which are:


This is a high-impedance output. Here, the internal bus keeper circuit remains active. The 3STATE_KEEPER needs Vcco to be at the recommended operating conditions.


This output behavior keeps driving the level that was previously stored in the output latch. Also, the DRIVE-LAST_VALUE needs Vcco to be at the recommended operating conditions.


This output behavior is in the high impedance state. Also, It has an internal pull-down resistor to GND.

  • 3STATE (default)

This is a high-impedance output without any active pull-down or pull-up resistor.

Differential I/O Standards

The differential input receivers and output drivers use up static power when utilized in FPGA. Furthermore, you have to disable differential outputs and inputs to save power during Suspend mode. The output drivers for differential I/O standards are high impedance. Also, during Suspend mode, differential input receivers disable.

ISE Design in Xilinx Spartan-3A FPGA

The effective utilization of programmable logic requires software. A set of Integrated Software Environment (ISE) by Xilinx supports the Spartan-3A FPGA. Also, the ISE features some design tools. These tools help to minimize project costs. Also, they help users to finish faster.

The ISE package is a series of design tools. Furthermore, these tools help to deliver the best productivity for logic performance in Spartan-3A FPGA.  Also, you can get the quickest runtimes in programmable logic with the ProActive Timing Closure. Therefore, you achieve your performance goals faster.

Also, the Incremental Design offers quicker re-compile times with great performance. The Xilinx ChipScope Pro verification tools offer real-time debugging. Also, the development system of the ISE helps you to quicken the logic design process. Therefore, this saves project cost and time.

The Design Flow

The design flow for Spartan-3A FPGA features three steps. You can select the desired result in Graphical User Interface (GUI) to run the entire design implementation flow. Also, these tools determine the files and programs required to update the appropriate output.

Design entry and synthesis

Here, you use a schematic editor supported by Xilinx to create your design. Also, you can use a Hardware Description Language (HDL). However, you need to convert the HDL file into an Electronic Data Interchange Format (EDIF) file.

Design implementation

You need to change the logical design format. Use the Xilinx Spartan-3 generation architecture to do this. Also, the EDIF created in the design synthesis or entry must change into a physical file format. You keep the physical information in the Native Circuit Description file.

Design verification

Make sure the design meets the functions and timing requirements. Also, achieving this is possible using a gate-level simulator. Furthermore, design verification often starts immediately after design entry. In addition, you can repeat this process after different steps of design implementation.


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 ISE Development Environment

The development systems have different configurations known as the ISE series. It is very easy to create Spartan-3A FPGA designs with the ISE development systems. Therefore, these ISE systems support design capabilities like integrated logic analysis and ProActive Timing Closure. Furthermore, the ISE solutions help designers to achieve quick and easy performance. The ISE tools offer the following features:

Design Entry

  • CORE Generator system
  • Schematic Editor
  • HDL Editor


  • Integration with Pro and Amplify synthesis
  • Integration with Precision synthesis
  • XST-Xilinx Synthesis Technology


  • Integration with Model technology’s ModelSim Simulator
  • ISE Simulator


  • Place and Route
  • Timing Analyzer
  • Map
  • XPower Power Analysis
  • Floorplanner
  • Translate
  • FPGA Editor

Device Download

  • iMPACT Configuration Tool
  • BitGen Bitstream Generator
  • ChipScope Pro Logic Analyzer

The project navigator is the basic user interface for the ISE tools. With this navigator, you can design, compile, and define your Spartan-3A FPGA design. Also, the Project Navigator manages every step of the design process.

More Facts on ISE Tools

Some ISE tools are explained below:

HDL Editor

This editor is specifically designed for editing HDL source files. In addition, the HDL editor offers syntax coloring. Also, this feature supports both Verilog and VHDL. Also, this editor functions as a standard test editor.

Xilinx Synthesis Technology (XST)

This features cutting edge design optimization techniques. The XST supports VHDL and Verilog design.

CORE Generator System

The CORE generator system by Xilinx offers a catalog of functions that ranges in complexity. There are simple arithmetic operators like multipliers, adders, and accumulators. Also, there are system-level building blocks like transforms, filters, and memory resources. The CORE Generator System generates a schematic symbol and a VHDL template file.

Timing Analyzer

This offers a flexible and powerful way to carry out static timing analysis. With this ISE tool, you can perform analysis after routing and mapping a Spartan-3A FPGA design. The timing analyzer confirms the delay along a particular path that meets the requirements of a specified timing.

ISE Simulator

This offers a full-featured HDL simulator built within the ISE development system. Also, ISE Simulator is available in two different versions

FPGA Editor

This is a graphical application that configures and displays FPGAs. The FPGA editor needs an NCD file. . In this file, there is the logic of your design mapped to IOBs and CLBs. Also, this editor can write to a Physical Constraints File (PCF).


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Spartan-3A FPGA Devices

XC3S400AN-FGG400AGQ    XC3S700A-4FGG484I XC3S700A-5FGG484C

XC3S700A-4FGG484C XC3S700A-4FG484I XC3S700A-4FGG400I


XC3S50A-4VQG100C XC3S50A-4VQ100C XC3S50A-4VQG100I

XC3S400AN-5FTG256C XC3S50A-4FTG256C XC3S50A-4TQG144C

XC3S400AN-4FGG400C XC3S400AN-4FG400I XC3S400AN-4FTG256C

XC3S400A-4FGG320I XC3S400A-4FGG400C XC3S400A-4FTG256C

XC3S200AN-4FTG256C XC3S200AN-4FT256I XC3S200AN-4FTG256I

XC3S200A-5FTG256C XC3S200A-5FGG320C XC3S200A-5VQG100C

XC3S200A-4VQG100C XC3S200A-4VQ100C XC3S200A4VQ100I

XC3S1400A-4FTG256C XC3S1400A-4FGG676I XC3S1400A-4FGG676C

XC3S200A-4FTG256C XC3S1400A-4FTG256I   XC3S200A-4FGG320C

XC3S400AN-4FT256I XC3S700A-5FTG256C XC3S400AN-4FT256C

XC3S50AN-4FTG256C XC3S400AN-5FT256C XC3S1400A-4FG676C

XC3S700A-5FGG400C XC3S700A-5FG400C XC3S700A-5FG484C

XC3S700A-4FTG256I XC3S700A-4FT256I XC3S700A-4FTG256C

XC3S700A-4FT256C XC3S700A-4FG484C XC3S700A-4FGG400C

XC3S700A-4FG400I XC3S50AN-4TQ144I XC3S700A-4FG400C

XC3S50A-5VQG100 XC3S50A-5TQG144C XC3S50A-5VQ100C

XC3S50A-5TQ144C XC3S50A-4VQ100I XC3S50A-5FTG256C

XC3S50A-4TQ144I XC3S50A-4TQ144C XC3S50A-4TQG144I

XC3S50A-4FTG256I XC3S50A-4FT256C XC3S50A-4FT256I

XC3S400AN-4FTG256I XC3S400AN-4FGG400I XC3S400AN-5FGG400C

XC3S400AN-4FG400C XC3S400A-5FTG256C XC3S400A-FTG256I

XC3S400A-5FT256C XC3S400A-5FGG320C XC3S400A-5FGG400C

XC3S400A-5FG320C XC3S400A-4FTG256I XC3S400A-5FG400C

XC3S400A-4FT256I XC3S400A-4FGG400I XC3S400A-4FT256C

XC3S400A-4FGG320C XC3S400A-4FG400C XC3S400A-4FG400I

XC3S400A-4FG320C XC3S400A-4FG256C XC3S400A-4FG320I

XC3S200AN-5FTG256C XC3S200AN-4FT256C XC3S200AN-5FT256C

XC3S200A-5VQ100C XC3S200A-5FG320C XC3S200A-FTG256AGQ

XC3S200A-4VQG100I XC3S200A-4FT256I XC3S200A-4FTG256I

XC3S200A-4FGG3201 XC3S200A-4FG3201 XC3S200A-4FT256C



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Features of XC3S400AN-FGG400AGQ

The XC3S400AN-FGG400AGQ FPGA belongs to the Extended Spartan-3A family. Also, this FPGA is ideal for various consumer electronics applications. It features:

  • Includes Hibernate and Suspend modes
  • Has about 227 differential signal pairs or 502 I/O pins
  • Comprises dual-range Vccaux supply
  • It is a high-end logic solution for costly applications
  • Has about 24 mA per pin
  • Multi-standard SelectIO interface pins
  • Enables 1.2V, 1.5V, 1.8V, 2.5V, and 3.3V signaling
  • QUIETIO standard minimizes Input/output switching noise

Features of XC3S400AN-5FTG256C FPGA

The XC3S400AN-5FTG256C FPGA is one of the extended Spartan-3A family. This FPGA has the following features:

  • Low-cost logic solution for highly priced applications
  • About 502 I/O pins
  • Hibernate and Suspend modes
  • QUIETIO standard which helps to reduce I/O switching noise
  • Output drive of about 24 mA per pin
  • Multi-voltage SelectIO interface pins
  • Full hot swap compliance
  • Dual-range Vccaux supply that simplifies 3.3V design only


The Xilinx Spartan-3A FPGA is a high-performance and low-cost solution for cost-sensitive applications. Furthermore, this FPGA is ideal for display devices that support PPDS and TMDs standards. Also, it offers the biggest support for I/O standards.



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