Temperature issues with Arria 10 transceivers and ATX pll for SATA interface

Hello.

We developed a custom board containing an Arria10 SoC (10AS048E2F29I1HG). We have connected a SSD via SATA to the pins of the FPGA. Internally, we are using an ATX pll, a transceiver core and a third party SATA core.

Everything works fine until the SoC reaches an internal temperature of 68°C (measured using Intel® FPGA Temperature Sensor IP Core).

At the moment, we try to isolate the root cause. Possibly, it could be the supply voltage, clock or PCB design (besides other issues off course).

• We measured the supply voltage for the transceiver near our DC/DC converter and we did not find something suspicious. Our next step is to measure the supply voltage close to the FPGA pin, since there are also capacitors involved.
• We checked the pll_locked signal using signal tap. No issues found. We also checked the transceiver reference clock with an oscilloscope. Clock looks good.
• For the PCB design, we did a signal integrity simulation to avoid this.

We already figured out that changing VCCT and VCCR has a big influence on the critical temperature ( the temperature when we see that the disparity errors start).

Short summary: 0.95V -> ~47°C, 1.03 V -> ~68° C, 1.1 V -> ~82° C, (we know that 1.1 V is out of spec).

We kindly ask you if you could support us to figure out what is going on. It would be great if you could assist us for the debugging of the interface. We hope that you can help us!

Thank you