Powering unused MGTs in XC4VFX20CES2
CASTalk.com Forum Index CASTalk.com
Discussion of DSP, FPGA, storage and embedded system.
 
 FAQFAQ   MemberlistMemberlist     RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 
Google
 
Web castalk.com
Powering unused MGTs in XC4VFX20CES2

 
Post new topic   Reply to topic    CASTalk.com Forum Index -> FPGA
Author Message
Peter Rauschert
Guest
Posted: Mon Dec 19, 2005 9:15 am    Post subject: Powering unused MGTs in XC4VFX20CES2 Reply with quote
Hi!

I just read the Virtex 4 documentation and the errata sheet for the
XC4VFX20CES2 device and I'm thinking about one aspect I found while
designing a PCB.

My design will not use any one of the included MGTs. I found in the
Xilinx answer database that even unused MGTs need to be powered. Here,
the AVCCAUXTRX/RX voltage in the errata sheet is 1.1V while it is -0.5
- 1.32 in the V4 datasheet.

Since I have a supply for VCCINT with 1.2V on my board, I'm wondering
if 1.1V are only neccessary to power used MGTs, while 1.2V can be used
to power unused MGTs in the CES2 device ??

Thanks,
Peter

Btw.: Do I need any filtering?
Back to top
Peter Rauschert
Guest
Posted: Mon Dec 19, 2005 9:15 am    Post subject: Re: Powering unused MGTs in XC4VFX20CES2 Reply with quote
Sorry, I forgot to ask another question. Since I'm using the ES2, the
transceiver pins for MGT_110 are not available.

Do I also need to power this MGT_110 with the suggested voltage?

Thanks,
Peter
Back to top
Austin Lesea
Guest
Posted: Mon Dec 19, 2005 5:15 pm    Post subject: Re: Powering unused MGTs in XC4VFX20CES2 Reply with quote
Peter,

The requirement to power unused MGTs is to meet ESD performance. If the
power and ground pins are left unconnected (to the MGT), it is unknown
what the ESD protection performance will be (basically, it is not tested
that way).

The voltage can be 1.2V (no issue with 1.1V, as you are not using the MGTs).

Also, filtering is not required (as they will not actually be enabled).

If one MGT is left unpowered, be sure the ground supply pin is connected
to ground, at a minimum.

Austin

Peter Rauschert wrote:

Quote:
Hi!

I just read the Virtex 4 documentation and the errata sheet for the
XC4VFX20CES2 device and I'm thinking about one aspect I found while
designing a PCB.

My design will not use any one of the included MGTs. I found in the
Xilinx answer database that even unused MGTs need to be powered. Here,
the AVCCAUXTRX/RX voltage in the errata sheet is 1.1V while it is -0.5
- 1.32 in the V4 datasheet.

Since I have a supply for VCCINT with 1.2V on my board, I'm wondering
if 1.1V are only neccessary to power used MGTs, while 1.2V can be used
to power unused MGTs in the CES2 device ??

Thanks,
Peter

Btw.: Do I need any filtering?

Back to top
Ed McGettigan
Guest
Posted: Mon Dec 19, 2005 11:16 pm    Post subject: Re: Powering unused MGTs in XC4VFX20CES2 Reply with quote
Peter Rauschert wrote:
Quote:
Hi!

I just read the Virtex 4 documentation and the errata sheet for the
XC4VFX20CES2 device and I'm thinking about one aspect I found while
designing a PCB.

My design will not use any one of the included MGTs. I found in the
Xilinx answer database that even unused MGTs need to be powered. Here,
the AVCCAUXTRX/RX voltage in the errata sheet is 1.1V while it is -0.5
- 1.32 in the V4 datasheet.

Since I have a supply for VCCINT with 1.2V on my board, I'm wondering
if 1.1V are only neccessary to power used MGTs, while 1.2V can be used
to power unused MGTs in the CES2 device ??

Thanks,
Peter

Btw.: Do I need any filtering?



The powering requirements for unused MGTs are to make sure that
everything on the part is in a known state. This means that you
can cut some corners for these MGTs. You can safely power the AVCCAUXTX
and AVCCAUXRX from your VCCINT 1.2V supply and not the 1.1V and you don't
need any power filtering on these pins.

You comment regarding 1.1V in the current errata vs -0.5 to 1.32V in the
V4 datasheet is a mistake. The former is for AVCCAUXTX/RX and the later
is only for the VTRX supply.

Ed
Back to top
Ed McGettigan
Guest
Posted: Mon Dec 19, 2005 11:17 pm    Post subject: Re: Powering unused MGTs in XC4VFX20CES2 Reply with quote
Peter Rauschert wrote:
Quote:
Sorry, I forgot to ask another question. Since I'm using the ES2, the
transceiver pins for MGT_110 are not available.

Do I also need to power this MGT_110 with the suggested voltage?

Thanks,
Peter


Yes you need to power this transceiver as well.

Ed
Back to top
 
Post new topic   Reply to topic    CASTalk.com Forum Index -> FPGA All times are GMT
Page 1 of 1

 
 You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum




VoIP Electronics Powered by phpBB