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AR# 4646

How to change XC4000XLA, XC4000XV, SpartanXL, and VIRTEX output drive current

説明


General Description:

For the XC4000XLA, XC4000XV, and SpartanXL devices, you can

change the output drive current for each IOB to either High(24mA)

or Low(12mA).

For the Virtex devices, you can select the output drive strength(mA)

for the components that use the LVTTL interface standard.

The applicable elements are:

1. IOB output components (OBUF, OFD, etc.)

2. OBUF, OBUFT, IOBUF instances (with implied LVTTL standards)

ソリューション


For the XC4000XLA, XC4000XV, and SpartanXL devices, the syntax is:

DRIVE = {12 | 24 }



For the Virtex devices, the syntax is:

DRIVE = {2 | 4 | 6 | 8 | 12 | 16 | 24 }

Note: Drive current can only be specified on the LVTTL I/O standard



This attribute can either be placed to a valid IOB output component

in a schematic or via a UCF/NCF file.



The syntax in a UCF/NCF file for example would be:



INST /top/my_design/obuf DRIVE = 24 ;



Where the instance name is the name of the OBUF

Or



NET <netname> DRIVE=24;



Where the netname is the net between the OBUF and OPAD
AR# 4646
作成日 08/31/2007
最終更新日 10/19/2011
ステータス アーカイブ
タイプ 一般