Answers Database

4000E/EX: Can the BUFGLS, BUFGE, and BUFFCLK (4000X) and BUFGP and BUFGS (4000E) be driven with Internal Logic?


Record #1795

Product Family:  Hardware

Product Line:  4000EX

Problem Title:
4000E/EX: Can the BUFGLS, BUFGE, and BUFFCLK (4000X) and  BUFGP and
BUFGS (4000E) be driven with Internal Logic?



Problem Description:
Keywords:
BUFGS, BUFGP, BUFGLS, BUFGE, BUFFCLK

Urgency:
Standard

General Description:

For 4000X parts  the BUFGLS (global low skew), BUFGE (global early) can all be
driven by either semi-dedicated pads or internal logic.  While
the BUFFCLK (fast clock) can only be driven by the semi-dedicated IOB's,
and is not accessible from internal nets.

For 4000E parts the BUFGS (Secondary Global Buffers) can be driven by either sem
i-dedicated pads or internal logic. While BUFGP (Promary Global Buffers) must be
 driven by the semi-dedicated pads.




Solution 1:

For a detailed description of each type of global clock buffer
in the XC4000X devices refer to pages 4-38 to 4-40 in the
1998 Xilinx programmable logic data book.



Solution 2:

For a detailed description of each type of global clock buffer
in the XC4000E devices refer to pages 4-36 to 4-37 in the
1998 Xilinx programmable logic data book.



End of Record #1795