Answers Database

What are the Thresholds for the Configuration Pins of the xc4000/E/L/EX/XL Families?


Record #2098

Product Family:  Hardware

Product Line:  4000E

Problem Title:
What are the Thresholds for the Configuration Pins of the
xc4000/E/L/EX/XL Families?



Problem Description:
Keywords: 4000, configuration, threshold, CMOS, TTL, CCLK, DIN

Urgency: Standard

General Description: What are the input and output thresholds
of the configuration pins of the xc4000 family of devices
before and during configuration, CMOS or TTL?

Note: All user I/O on our 5V parts (4000E and 4000EX) families
have programmable thresholds on all of the inputs and outputs
after the device is configured but the configuration pins have
a defined threshold (see below) since the device is not yet
configured.

The I/O on our 3V parts (XC4000L and XC4000XL) have CMOS level
I/O and do not have programmable thresholds. See Solution 2760:

http:/www.xilinx.com/techdocs/2760.htm


Solution 1:

In all our 5-V parts (XC4000, XC4000E, XC400EX) the input and
output thresholds are TTL on all configuration pins, until the
configuration has been loaded into the device and specifies to
use otherwise.

In all our 3-V parts (XC4000L, XC4000XL), everything is CMOS
thresholds in and CMOS levels out.



End of Record #2098