Description

Urgency: Standard

General Description:

Atmel makes EEPROM-based devices that they claim are pin compatible

with Xilinx 1700 devices. They are named in a similar fashion as Xilinx

PROMs-- 17Cxxx-- 17C65, 17C128, for example. Although they are pin-

compatible, they are not design-compatible.

Xilinx has not qualified these parts for use in configuring Xilinx FPGAs.

Solution

Although the Atmel parts are spec'd the same, there are some

significant differences between the Atmel EEPROMs and Xilinx

serial PROMs:

1. Atmel PROMs are not compatible with Xilinx FPGA Express

Mode configuration because they are not fast enough.

2. There is incompatibility in how pin 7 (VPP), the

programming voltage pin, is connected to Vcc. During

operation, this pin must be connected to VCC for Xilinx serial

PROMs. Atmel uses the same pin as an active low serial

enable input for in system reprogramming. Because of this

difference, the Atmel parts cannot be considered as drop-in

replacements.