Forum Discussion
Arria II EP2AGX45CU17C6N power up failure.
Hi all,
I am using Arria II EP2AGX45CU17C6N FPGA in my PCIe interfacing card project, I had only one FPGA device mounted on PCB and power section. Power voltage rail on PCB board 3.3V & 0.9 (sw_reg - Dual O\P) | 2.5V (LDO) | | 1.5 & 1.1V (LDO - Dual O\P) On doing Initial power supply check in PCB only some FPGA VCC pins Receives voltage Vccio = 3.3V , Vcc =0.9V ,Vccl_GXB=1.1V,VccH_GXB=1.5V And VCCA=2.5V. but other pins like vcca_pll(2.5v),vcc_pll(0.9v) and vccb(1.5v) are open (isolated from getting powered by removing ferrite bead component on pcb) At this point I measured Voltage rail, all voltage output are fine and as per expected (no Heat on FPGA and regulators) After some time i mounted all the components and powered up the board so that other VCC and PPL pins also receives voltage VCCA_PLL (2.5V),VCC_PLL(0.9V) and VCCB(1.5V),At this time I found VCCB(1.5V) Pins got shot to GND pin also 1.5V LDO and FPGA got heat. I switched of Supply and check the impedance now VCCB pin of FPGA and GND Pin is Short (Z = 0 ohm), I came to know VCCB pin of FPGA got gone bad, my query, 1. Can i connect only some FPGA VCC pin to respective voltage initially (not connecting PLL and VCCB pins,. connecting these PINs second time power on)?? Will devices pin go bad on second power up?? 2. Should I connect all the power supply pin of FPGA including PLL and VCCB every time power up for device to work properly?? not to get spoil of any pins?? Note:- Last option... I might have received fault\damage FPGA but it’s my last option getting bad FPGA chip from standard manufacturing is very least possibilities...21 Replies
- Altera_Forum
Honored Contributor
Hello,
yes, all De-Caps for VCCA_PLL(2.5V) are mounted before power up. - Altera_Forum
Honored Contributor
hi
have you found the cause of FPGA's PLL power pin shorted-circuit to GND. we have same problem in 2 of our boards. we are using EP2AGX95EF35C4N. VCCA_PLL pins are shorted to GND. Regards, Arvind. - Altera_Forum
Honored Contributor
Hi,
Yes as per RMA result FPGA IC is prone to overshoot of supplies. And as per my analysis, There could be two reasons one Overshoot \ Voltages on rail out of tolerance (Eg:- 1.5V vccb could be 1.425 - 1.575) and other cause may be ESD....... - Altera_Forum
Honored Contributor
hi,
we are using linear power supply, and its with in the range.there is no overshoot. chances of ESD is less in our case. what type of filtering you are using for pll supply? regards, Arvind. - Altera_Forum
Honored Contributor
the board was working for 1 year, before it failed with VCCA_PLL shorted to GND.
- Altera_Forum
Honored Contributor
Hi we use,
Ferrite bead Chip 33 ohm @ 100Mhz as PLL supply filter. can you see your FPGA board power rail voltages and IC used...?? - Altera_Forum
Honored Contributor
Hello arvindk, we had a similar problem with ARRIA II GX EP2AGX65DF25C6 (after power up we found VCCA_PLL(2.5V) pins shorted to GND). We had two pieces of FPGA in Altera Failure Analysis Center in Malaysia and they said us, that we damage the die of lidless FCBGA package(bottom corner) by mounting a heat-sink with push pins. Do you use a heat-sink?
- Altera_Forum
Honored Contributor
Hi Joey, yes we are using heat-sink with push pins from AAVID (10-5607-05G). we are also using lidless FCBGA package, and its bottom right is damaged. So this could be the reason. we will be sending the FPGA to Altera Failure Analysis Center soon. We replaced the FPGA and now its working. our board was proto board and we had removed the heatsink couple of times.
- Altera_Forum
Honored Contributor
heat-sink with push pins from AAVID (10-5607-05G). www.aavid.com/products/bga/10-5607-05g .
- Altera_Forum
Honored Contributor
Hi arvindk, we solved the problem by using a gap-filler between heat-sink and chip. If you would like more information(our solution, application notes...) I can give you via email. If you can, write me a email address.