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AR# 34198

Virtex-6 Configuration - How should a 3.3V SPI device be connected to a V-6 running at 2.5V?


In Virtex-6 devices Vcco runs at a maximum of 2.5V and most SPI flash devices on the market run at 3.3V.
How should the two devices be interfaced?


The SPI interface is a 4 pin interface.
The outputs of the Virtex-6 device to the SPI are the CCLK, DO, and CS pins. 

For most SPI flash devices, the inputs will recognize 2.5V as a high, and this can be checked with the flash vendors Vihmin specification.
The input to the Virtex-6 device from the SPI is the DIN pin, and this will be supplied from the SPI device at 3.3V.

A pull-down on this line at 120 ohms should be able to take care of the level translation for this signal.
In summary, the outputs from the Virtex-6 device should be able to drive the inputs to the SPI device, and the input to the Virtex-6 device can be handled with a 120 ohm pull-down.
AR# 34198
Date 12/05/2014
Status Active
Type General Article
  • Virtex-6 CXT
  • Virtex-6 HXT
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