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Contributor
Contributor
8,302 Views
Registered: ‎11-24-2009

Spartan 6: What to do with unused Transceiver banks?

Hello,

 

I'm drawing out a design for a Spartan 6 which does not require the use of transceivers but, owing to a number of other considerations, I'm still using a 45T device.

 

What should I do with the unused Transcever banks (101, 123 and a few dedicated signals)?  I can't find any guidance in the documentation (it's a strange thing to pay extra for a T device and then not use the transceivers, so this is understandable!).  Any advice or points in the right direction would be greatly appreciated.

 

Many thanks in advance for any assistance in this matter.

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9 Replies
Xilinx Employee
Xilinx Employee
8,294 Views
Registered: ‎01-03-2008

Re: Spartan 6: What to do with unused Transceiver banks?

The Spartan-6 GTP User Guide has a section titled "Managing Power Supply Connections for Used and Unused GTP Transceivers" that provides the information you are looking for.
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Visitor kgroll
Visitor
8,270 Views
Registered: ‎01-24-2010

Re: Spartan 6: What to do with unused Transceiver banks?

I ran into the same problem with a V6 part, where I needed the additional DSP resources of a T part, but plan on using zero transceivers.  Frustrating indeed, but I'm not at the point in my design where I've had to consider the solution.

 

It appears that mcgett has the answer though.  I believe he's referring to this document: http://www.xilinx.com/support/documentation/user_guides/ug386.pdf and, more specifically, Page 166.

 

I'm quoting an excerpt from it here:

 

 

 

If only one of the GTP DUALs in a GTP Bank will be used in an application, the unused

GTP DUALs can be unpowered. The power supply pins for the unpowered GTP DUAL

must be connected to ground.

If only one of the GTP DUALs in a GTP Bank will be used and the second GTP DUAL is

unpowered, the powered GTP DUAL must be GTPA1_DUAL Tile 0 and the unpowered

GTP DUAL must be GTPA1_DUAL Tile 1. The reason for this requirement is that power

for the termination resistor calibration circuit is from the MGTAVTTTX power pin on

GTPA1_DUAL Tile 0.


 

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Contributor
Contributor
8,265 Views
Registered: ‎11-24-2009

Re: Spartan 6: What to do with unused Transceiver banks?

Cheers for that clarification guys.

 

I've tied the  MGTA VCC, TTTX and TTRX to ground.  I've also tied the VCCPLL0 and 1 pins to ground as I notice that these PLLs can only be used with the Transceiver logic.  Finally, I've tied the RX pins to ground and left the TX pins floating.  Do you have any suggestion on what to do with the MGTAVTTRCAL and MGTRREFpins on the dedicated bank?  For now I've left the former connected to a 1.2V supply and the latter connected to1.2V via a precision 49.9 ohm resistor as was done in the evaluation board schematics.  I'm assuming that if the Transceivers are powered down, I can leave both of these ports connected to ground...

 

Anyways, thanks again for the advice and, to provide some feedback, I'll do a little necromancy on this post once the board is built.

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Xilinx Employee
Xilinx Employee
8,256 Views
Registered: ‎01-03-2008

Re: Spartan 6: What to do with unused Transceiver banks?

The MGTAVTTRCAL and MGTRREF pins should be grounded or left unconnected in your case.  Tieing them to a voltage supply while all of the other supplies are at ground might be an issue. 

 

 

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Visitor matme
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Registered: ‎11-21-2011

Re: Spartan 6: What to do with unused Transceiver banks?

When the GTP's are unused/unpowered (according to ug386, table 5-3), is it still possible to use boundary scan?

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Xilinx Employee
Xilinx Employee
7,099 Views
Registered: ‎01-03-2008

Re: Spartan 6: What to do with unused Transceiver banks?

In Spartan-6 the powered state of the GTPs does not effect the operation of JTAG boundary scan operations.

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Contributor
Contributor
7,075 Views
Registered: ‎11-24-2009

Re: Spartan 6: What to do with unused Transceiver banks?

Ah well, I did promise to come back to this at some point.  Just to confirm that the suggested configuration for unused Spartan6 Transceiver banks is working fine on our boards.  We can also do JTAG boundary scans on the device.  Thanks once again for the help.

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Visitor okar
Visitor
6,662 Views
Registered: ‎02-28-2013

Re: Spartan 6: What to do with unused Transceiver banks?

Hello,

 

if I want to power down the transceivers temporary there exist several power-down modes described in ug386. I can't find any value for the minimal supply current of the transceivers if I use all these power-down modes (TX, RX and PLL powerdown ). I think there is at least a static current isn't it?

In datasheet there is only a value for a powered but unconfigured device (table 15 DS162).

 

Is it possible to switch off the transceiver supply and connecting it to ground as described in ug386 although, as in my case, the transceivers are configured? If once powered down I don't use the transceivers until the next fpga configuration.

 

Can anybody help?

thanks.

 

 

 

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Newbie nishu_1212
Newbie
3,055 Views
Registered: ‎09-21-2015

Re: Spartan 6: What to do with unused Transceiver banks?

The documentation has information about unused Duals and Banks, but what is the recommended connection for an unused lane (TX/RX) pair, in a dual where the other lane is used.

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