FPGA is hot

There are two issues, that are likely to cause excessive current consumption:

- floating input pins

Clock pins don't have an option to set a defined level by configuration and must be externally terminated. Other unused pins should be e.g. configured as input with weak pull-up.

- shorted output pins

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I'm using EP1C6Q240 FPGA, after programming it , the current for 3V3 was about 400mA, working OK, after several weeks, the current went to about 800mA and FPGA was getting hot, but it's still working.

Does anybody know why the FPGA is getting hot?

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Hi,

check the default setting of unused pins. You can find the setting under:

Assignments -> settings -> Device and Pin options -> unused Pins

As FvM mentioned should be set to "As input tri-stated with weak pull-up"

Kind regards

GPK

--- Quote Start ---

There are two issues, that are likely to cause excessive current consumption:

- floating input pins

Clock pins don't have an option to set a defined level by configuration and must be externally terminated. Other unused pins should be e.g. configured as input with weak pull-up.

- shorted output pins

--- Quote End ---

Hi! FvM!

You said that "shorted output pins" is a possible issue to cause excessive current consumption . I can't undersant that . can you descript it in detail?

many thanks!

shorted output pins means pins connected to ground or a logic output in the external circuit, but driven in the FPGA unintentionally, e.g. due to wrong or incomplete pin assignment.

I experienced, that the setting of configuring unused pins as output, that has been a default with previous Quartus versions, increased the risk of getting unintentionally shorted output pins.

The reason was found, it's because we connected VCCA_PLL1 and VCCA_PLL2 to 3.3V. according to data sheet, this was wrong, those VCCA pins should connect to 1.5V.

After doing that, the FPGA is cool now, the problem is the FPGA cannot be programmed. if I changed VCCA back to 3.3V which was wrong, it could be programmed and then became hot again. I don't know why this happens.