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Visitor singularwoo
Visitor
880 Views
Registered: ‎08-12-2018

some pins of a bank no ouput

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I have encounted a strange problem.
All pins worked normally before. But from yestaday, some pins of a bank(vcco=3.3) just seems destroyed. The input pins are still normal, while the output and inout pins no longer work. I can measure nothing with a ossiloscope. Pins of other banks are normal. How could this happen? What can I do now?
Many thanks!
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1 Solution

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Moderator
Moderator
896 Views
Registered: ‎09-18-2014

Re: some pins of a bank no ouput

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Singularwoo,

 

Well, without taking a detailed look at your design, operating conditions and environment it is difficult to pin point exactly what may have caused this. Even when doing so if that part is already clearly damaged it can lead you on a wild goose chase as damage can cause a chain reaction of other issues within the device that may have had nothing to do with the original source or root cause. In any case review with either your board design engineer or local Xilinx FAE to find out how and where the device was operated outside of the data sheet specc'ed operating conditions. Run through the schematic checklist, PCB guide, check your power sequencing(remember no hot swapping/plugging! At least not without proper proper design measures shown in XAPP1311), check for device temp, erroneous designs, etc. See our WP433. Read it carefully in detail. Work down the fish-bone diagram in Figure 3 to checkoff your design and areas where EOS or ESD could have occurred. I also recommend taking a look at the Industry council JEDEC presentation and/or white paper  for additional information about the nature of semiconductor damages. 

 

Regards,

T

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9 Replies
Xilinx Employee
Xilinx Employee
850 Views
Registered: ‎06-02-2017

Re: some pins of a bank no ouput

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Hi singularwoo,

 

You can check the bank supply voltage first.

As you said these pins worked well before, what're the standard they were? And what'd the voltage for these bank? 

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Visitor singularwoo
Visitor
841 Views
Registered: ‎08-12-2018

Re: some pins of a bank no ouput

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The iostandatd of this bank is lvcmos33.The vcco voltage measured with multimeter is 3.345, which is below 3.465v. Now the total current has increased by 200mA(28v), and fpga is very hot.
Do you understand Chinese?I can describe it in Chinese in detail.
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Scholar drjohnsmith
Scholar
803 Views
Registered: ‎07-09-2009

Re: some pins of a bank no ouput

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generally speaking, if a chip is very hot unexpectedly,

 

then you have a short or wrong voltage to the chip.

 

 

Visitor singularwoo
Visitor
793 Views
Registered: ‎08-12-2018

Re: some pins of a bank no ouput

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Thanks!
I measured all the supply voltage, and they are all normal. does that means the chip is inner short and it as been destroyed?
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Visitor singularwoo
Visitor
792 Views
Registered: ‎08-12-2018

Re: some pins of a bank no ouput

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By the way, what may result in short of fpga as this?
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768 Views
Registered: ‎01-22-2015

Re: some pins of a bank no ouput

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FPGA digital outputs are tolerant of short-to-ground conditions (see AR#23255).  So, perhaps your FPGA is not damaged.

 

For the FPGA outputs with problems, can you remove the devices being driven – and use oscope to see if the FPGA outputs then toggle to proper levels?

 

Also, be aware that each bank of the FPGA has a total input-current limit.  This limit is usually shown in Table 1 or Table 2 of the datasheet for your FPGA.  For example, the Kintex-7 has a input-current-limit-per-bank of 200mA as shown by I(IN)-footnote(9) specification found in Table 2 of Xilinx document, DS182.

 

Mark

 

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Visitor singularwoo
Visitor
762 Views
Registered: ‎08-12-2018

Re: some pins of a bank no ouput

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finally, i find that ther are shorts in vccint and vccaux, and others suply voltage are still normal. The chip is extreamly hot , and the total supply current with 28v reached almost 250mA for fpga only. So it seems that this chip has been destroyed. Now I want to know what may lead to this and I need to change my design to avoid the destroy.
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Moderator
Moderator
897 Views
Registered: ‎09-18-2014

Re: some pins of a bank no ouput

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Singularwoo,

 

Well, without taking a detailed look at your design, operating conditions and environment it is difficult to pin point exactly what may have caused this. Even when doing so if that part is already clearly damaged it can lead you on a wild goose chase as damage can cause a chain reaction of other issues within the device that may have had nothing to do with the original source or root cause. In any case review with either your board design engineer or local Xilinx FAE to find out how and where the device was operated outside of the data sheet specc'ed operating conditions. Run through the schematic checklist, PCB guide, check your power sequencing(remember no hot swapping/plugging! At least not without proper proper design measures shown in XAPP1311), check for device temp, erroneous designs, etc. See our WP433. Read it carefully in detail. Work down the fish-bone diagram in Figure 3 to checkoff your design and areas where EOS or ESD could have occurred. I also recommend taking a look at the Industry council JEDEC presentation and/or white paper  for additional information about the nature of semiconductor damages. 

 

Regards,

T

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Visitor singularwoo
Visitor
753 Views
Registered: ‎08-12-2018

Re: some pins of a bank no ouput

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Thanks! I'll check the design as you've said.
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