Unusuall heating of fpga

[rashmi.imhsar]

My cyclone 3 fpga is getting heated up very fast in a few seconds after switching on the power even before burning the code.

The adapter is working fine and so there is no problem with the power supply. What could be the reason for this unusual heating?

It got heated in a few seconds !

 

[shahulakthar]

First check for short circuit.

 

[rashmi.imhsar]

First check for short circuit.

I feel that one of the capacitors would have gone. How do I check which capacitor is gone?

 

[FvM]

I presume you checked for correct supply voltages? You should determine which supply pins are sinking excessive current (IO-banks, core supply,...). In case of IO-bank overcurrent I would expect a damaged IO buffer. Excessive core current suggests previous supply overvoltage. In both cases, I fear the FPGA is gone.

 

[shahulakthar]

I feel that one of the capacitors would have gone. How do I check which capacitor is gone?

What are the voltage you are providing to FPGA?
Did you check individual voltage for shot circuit before Powering?
Also provide information on IC package and did the board work previously ?

 

[rashmi.imhsar]

What are the voltage you are providing to FPGA?
Did you check individual voltage for shot circuit before Powering?
Also provide information on IC package and did the board work previously ?

Hi,

yes the board was working fine previously. Am working on interfacing a ADA_THDB board to my Cyclone 3 starter kit. The latest edition i did when it started to heat was adding a PLL to increase the clock frequency . MY fpga provides only 50MHZ , while the update rate of the DAC is 125MSPS . So could it be that as i increased my clock frequency to 100 mhz the corresponding FPGA capacitance would have got affected?

Also there are a lot of buried capacitance behind the FPGA, How do we check these capacitance?

Thanks ,

sindhu

 

[FvM]

I rely on your statement that the FPGA overheats without being configure before. That means of course, you have to be sure that no faulty configuration has been loaded from the configuration flash. The unconfigured FPGA holds all pins in high impedance state and doesn't source or sink excessive current on any signal pin.

I don't see any point related to capacitance.

 

[rashmi.imhsar]

I rely on your statement that the FPGA overheats without being configure before. That means of course, you have to be sure that no faulty configuration has been loaded from the configuration flash. The unconfigured FPGA holds all pins in high impedance state and doesn't source or sink excessive current on any signal pin.

I don't see any point related to capacitance.

Hi,

All the unused pins are configured to inputs tri-stated to weak pull-up . Besides I also tried burning a basic AND gate code, it had none unused pins. Even then the FPGA started to heat. Now even without loading any code, just switching on the board causes the FPGA to heat. So what are we mainly supposed to check in the FPGA?

I checked the FPGA core voltage its only around 1.25 V

Thanks

 

[rashmi.imhsar]

I have found out that the "JP3 Sense resistor for measuring the power consumed by the 2.5 V supply to VCCIO, the DDR, the flash I/O, and the SSRAM" has been shorted.

Also, "JP6 Sense resistor for measuring the power consumed by the 1.2 V
VCCINT supply to the Cyclone III device" has been shorted.

The kit I am using is Cyclone 3 FPGA Starter kit.

What I do not understand is,how can the other jumpers be intact and only the cyclone 3 FPGA related jumper is alone shorted?