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AR# 564

FPGA COMPILER: PULLUPs/PULLDOWNs must be instantiated when using Synopsys.

Description


Can PULLUPs and PULLDOWNs be inferred or do they have to be instantiated ?

Solution

PULLUP and PULLDOWN components may be inferred on pad connections of input and
output cells. These I/O cells have attributes that allow you to infer PULLUP or PULLDOWN
resistors using the set_pad_type command in Synopsys tools.
For example, to attach a PULLUP resistor to an input port named INPUT1, type:

set_pad_type -pullup INPUT1

Internal PULLUPs must be INSTANTIATED, they cannot be inferred.


AR# 564
Date Created 09/20/1995
Last Updated 11/08/2004
Status Archive
Type General Article