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AR# 760

FPGA Configuration: XC4000E won't configure in socket designed for XC4000?


General Description:

In rare cases, you may find that an equivalent XC4000E device

does not configure when dropped into your existing XC4000 socket.


You may encounter this problem if your design:

1. Configures in peripheral, master parallel,

or master serial mode

2. Uses one or more mode pins as signal pins, AND

3. Has pull-down resistors over 5k on one or more mode pins.

Note that all three of these criteria have to be met for

this problem to occur.

Change the high-resistance pulldowns to resistors of 5k or below.

AR# 760
Date 12/15/2012
Status Active
Type General Article