cyclone3 fpga device failure

Altera_Forum · ‎05-13-2011

i have designed a board in which i am using 3 cyclone 3 fpga devices. one of them is EP3C16 and other two are EP3C5.one of these EP3C5 deviCes works fine for some days and then automatically gets bad without any malhandling.this is happening in all the boards. after observation we have found that 2.5v of this device draws heavy current.after replacing the device it then works fine in all the cards.please let me know why is this happening.

Altera_Forum · ‎05-13-2011

Some ideas:

Do you have an output driving high current? i.e. do you directly drive LEDs or any other current consuming device?

Is the device hot during normal operation, before failure?

Are you sure you don't have some rare abnormal condition when two of those fpgas drive the same line with opposite levels?

Does the device gets damaged during operation or do you find it damaged after power up?

Altera_Forum · ‎05-18-2011

Hi Cris72,

I read the ideas mentioned by you.Below are some of the clarification regarding tha----

1.We are driving LEDs directly by the FPGA (with series resistance).LED draws 10mA current typically.

2.Device is getting damaged while operation.

3.We could no found any abnormal condition beween two FPGAs as mentioned by you.

4.We could not monitor the device heating before failure because device is getting failed during operation randomly.

Do you want the schematic of the device,in our design,for review?

Altera_Forum · ‎05-18-2011

Default I/O standard for CIII is 3.3V LVTTL or 3.3V LVCMOS which have a current strength of 4 or 2 mA respectively. Did you change the default with a higher strenght value?

I don't know if this could affect DC operation, causing output stage overheating and damage; probably current strenght affects only AC operation, i.e. it improves switching speed. Anyway you'd better check this point.

Another point to consider is the maximum consecutive pins driving high current; this must be limited to a value reported in CIII datasheet.

Could this be your situation? Do you have many LEDs? I mean 20 or more; if you do, the pin driving them should be spread across banks around the fpga and not concentrated in a single side/corner.