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Visitor akshitsood
Visitor
2,800 Views
Registered: ‎07-06-2011

SPARTAN6 LX45 CSG484

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HI

 

I am planning to use the device XC6SLX45-3CSG484. For assigning pin list i am using Xilinx PLan Ahead v 11.5.

NOw while assigning pins to a bank i assign LVCMOS25 input to a bank with VCCO and VCCAUX 3.3 and all other signals in the bank are LVCMOS33. So it gave a warning saying Either VCCO or VCCAUX must be 2.5V to support the LVCMOS25 inputs in a bank with all other LVCMOS33 signals.

 

 

So am i allowed to have feeed LVCMOS25 inputs.

What will be the effect if i change the VCCAUX to 2.5 V on the rest .

 

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Teacher eteam00
Teacher
3,463 Views
Registered: ‎07-21-2009

Re: SPARTAN6 LX45 CSG484

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There are some signaling standards which require VCCAUX = 3.3V.  Specifics are found in DS162.

 

LVCMOS25 input requires either VCCO=2.5V or VCCAUX=2.5V.  Reference DS162, Table 7, note 1.

 

If the source driver for an LVCMOS25 input signal can tolerate 3.3V, then suggest you use LVCMOS33 input with an external R pullup to 3.3V.

 

-- Bob Elkind

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Visitor hallovipin
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Registered: ‎06-15-2010

Re: SPARTAN6 LX45 CSG484

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It said correctly. If you need to have LVCMOS25 inputs either you have to make VCCAUX 2.5 volts or the bank which has LVCMOS inputs you power it up with 2.5 V instead of 3.3 Volts. 

 

I am not sure but I think the best solution will be powering all your VCCIOs with 3.3 volts and VCCAUX with 2.5 volts.

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Teacher eteam00
Teacher
3,464 Views
Registered: ‎07-21-2009

Re: SPARTAN6 LX45 CSG484

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There are some signaling standards which require VCCAUX = 3.3V.  Specifics are found in DS162.

 

LVCMOS25 input requires either VCCO=2.5V or VCCAUX=2.5V.  Reference DS162, Table 7, note 1.

 

If the source driver for an LVCMOS25 input signal can tolerate 3.3V, then suggest you use LVCMOS33 input with an external R pullup to 3.3V.

 

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
7. You are not charged extra fees for comments in your code.
8. I am not paid for forum posts. If I write a good post, then I have been good for nothing.

View solution in original post

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