UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 24365

Spartan-3/3E/3A - What is the nominal VCCO value for PCI33_3 and PCI66_6?

Description

Keywords: Spartan-3E, s3e, PCI33, PCI66, PCI, Vcco, S3A, S3, Spartan-3A, Spartan-3, PCI, Power, rail, XAPP653, XAPP457

The Spartan-3 and Spartan-3E Data Sheets state that PCI_33 and PCI_66 VCCO requirement is 3.3V with a range of -10% to +5% (3.0V to 3.45V).

Does this mean that the Spartan-3/3E can be connected directly to the PCI 3.3V power rail?

What about Spartan-3A?

Solution

The reduction in VCCO discussed in XAPP653 is no longer required for Spartan-3 Generation FPGAs based on revisions to the absolute maximum ratings specification for the VIN parameter (the voltage applied to all user I/O pins). Existing designs that use this technique continue to be valid; however, all new designs should take advantage of the enhanced absolute maximum ratings specification. Please see XAPP457 for more information on powering Vcco for Spartan-3 family devices. This application note can be found at: http://direct.xilinx.com/bvdocs/appnotes/xapp457.pdf

Summarizing XAPP457 -

Spartan-3 and Spartan-3E PCI buffer VCCO Requirement

For Spartan-3 and Spartan-3E devices, the data sheets reflect that the VCCO requirement is 3.3V with a range of -10% to +5% (3.0V to 3.45V). For existing Spartan-3 and Spartan-3E designs using a regulated VCCO to 3.0 volts, no changes are needed as this continues to be compliant. For new Spartan-3 and Spartan-3E PCI designs, it is still necessary to regulate VCCO because the PCI Specification specifies the PCI power rail to be 3.3 volts +/-10%(3.0V to 3.6V). This means a regulator is still required for Spartan-3E. However, the voltage can now be regulated to 3.3 volts instead of 3.0 volts.

Please refer to XAPP457 and the LogiCORE Initiator/Target for PCI Getting Started Guide for more information on the recommended regulator and circuit to meet these requirements.

Spartan-3A PCI buffer VCCO Requirement

No VCCO regulation is required. Spartan-3A VCCO is 3.3V, +/- 10%, which allows for VCCO to be directly connected to the PCI bus power.


AR# 24365
Date Created 12/06/2006
Last Updated 06/26/2007
Status Active
Type General Article