04-07-2016 01:20 AM
I am using board based on XC7K325T-2FBG900(Kintex-7).
1) my circuit design uses approximately 30~40% of FPGA resources. (and not used latch in my circuit design)
2) main clock is 200MHz(LVDS).
3) there is the heat sink on top of the chip package.
4) confirmed the power applied to the FPGA.
But FPGA is hot. very very hot.
XPE result is 50 ~ 60 ℃.
As confirmed by chipscope, the temperature of the chip was increased to more than 100 degrees.
I know the resolution of fever as in the following list.
1) low clock speed
2) design optimize
3) operate with a better heatsink
4) use an industrial temperature range device
5) split the design into two smaller device
6) using a lot of ground on the board
7) using enough decoupling capacitors on the board
So i had to test.
using 200MHz (LVDS), blinks the LED every 1 second.
this circuit design uses approximately 1% of FPGA resources and the chip temperature was 47℃.
I think there is a problem about which the chip is hot.
What if this is normal?
if non-normal, Please advise other reasons or solution.
thank, have a nice day! :)
04-08-2016 04:04 AM
If this device is on a KC705 evaluation board then you could try the XADC reference design that is provided with the KCPSM6 version of PicoBlaze (available from http://www.xilinx.com/ipcenter/processor_central/picoblaze/member/ ). This reference design also uses some circuitry running at 200MHz and plots a simple temperature graph. As shown in the documentation provided with the design I personally saw the temperature rise from 20C to 26C over a period of about 3 minutes and that increase only occurred when I unplugged the heat sink fan. As such it does sound like your device is running a bit hot. If it’s mounted on a custom board (i.e. not a KC705 board) then it would be worth checking pin-outs to check that there isn’t a mistake somewhere that is causing a lot of current to flow from one or more of the power suppy rails.
04-08-2016 06:31 AM
if your PCB is not very large 16 layer one, then 47C at room with "empty" FPGA is normal not at all too hot.
if you run 30-40% of K325T at 200mhz, then you need a pretty good cooling.
you can not expect to see junction temperatures as forecasted by XPE in real designs. There are many factors that makes the actual temperature higher.
So seeing junction reaching 100C in K325T, 200mhz 40% is pretty normal.
10-17-2016 07:41 PM
If some of the OUT IO pins are set wrong then a-lot of current can be going through them.
Logic-1 into ground or the opposite.
Or an OUT connected to an external OUT can cause fighting.
Incorrectly assigned inputs shouldn't cause heat.
That will get hot with no clock.