AR# 6768

描述

Are Virtex devices hot-swap compliant?

If so, what circumstances affect the devices' ability to be hot-swapped?

解决方案

For Virtex devices

Yes. Virtex devices can be hot-swapped.

No power sequencing issues exist (VCCO, VCCINT, I/Os can be powered-up in any order). For more information, see (Xilinx Answer 5133).

You can elect to include internal pull-up resistors before and during configuration by selecting the appropriate levels on the three mode pins. When you select the "No pre-configuration pull-up" option, the I/O leakage current will be within +/- 10 uA after VCCINT has reached 2.375V (minimum nominal VCCINT value). The leakage current will also be within +/- 10 uA on I/Os during configuration (except for the /INIT pin, which always has a weak internal pull-up attached to it).

For Virtex-E devices

Please see (Xilinx Answer 10129) for information on power-sequencing conditions.

Before configuration, NO clamping diodes are available for Virtex-E devices, and the I/O pins behave like I/Os in a 3-state condition. For this reason, it is permissible to drive un-powered I/O.

After configuration, clamping diodes are available for certain I/O standards. See (Xilinx Answer 9050) for more information.

The clamping diode is ~0.7 to VCCO and -0.5 to GND, so 4.3 is generally the maximum voltage that can be used to drive I/Os before the diodes to VCCO become forward-biased.

For Virtex-II, Virtex-II Pro, Virtex-4, and Virtex-5 devices

The clamp diodes in the I/O pins are always present.

Please see the Xilinx Application Note (Xilinx XAPP251): "Hot-Swapping Virtex-II, Virtex-II Pro,

Virtex-4, and Virtex-5 Devices" for more information on hot-swapping these devices:

http://www.xilinx.com/support/documentation/application_notes/xapp251.pdf