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Altera_Forum
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16 years ago

FPGA Thermal Burn out

I am using a FPGA EP3C25F324C8N on my board. I as conducting a thermal testing on this board. When the ambient temperature of the chamber was 42deg C, the FPGA case temperature was 62degC.. Suddenly the temperature raised to 80degC and the device got burnt..

Based on the Cyclone 3 data sheet, the R(ja) is 26.6 and max junction temperature is 85deg C. The power dissipation is about 1W in the FPGA.

With these calculations, the FPGA should not burn-out..

Do you see any other issues with this?

Thanks,

Raghu

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Did you use the power estimator tool? What was the temperature calculated by the tool?

    Others factors can heat the fpga, like Unused pins drive GND and have VCC on hardware connected at this pins. Take a look in this option on Device Setting of quartus.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I have never seen the FPGA temperature jump very quickly... it is usually a slow steady rise. If this is the case it is probably a short or contention on a IO pin..

    We usually have a temperature monitoring chip on our boards and configure the temp alert signal to un-configure the FPGA... this may help protect your devices..
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I would expect a fair margin between rated maximum junction temperature, which surely matters for keeping e.g. the timing specification, and damage of the chip. The latter should be considerably above 125 °C. So I guess, that something dramatic happened to your circuit, e.g. a power supply was running wild. Or a previous existing FPGA defect.