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Newbie
Newbie
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Registered: ‎05-18-2019

ZC7010 thermal dissipassion when using ddr

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Hi, The thermal dissipation of zc7010 is quit high after ddr3 initializing. The initialization program is generated by sdk, ddr3 operates in 533Mhz. The temperature of FPGA chip go up over 60 degrees if ddr3 was enabled, and decrease obviously when ddr3 was disabled. Anyone has encountered the same problem?
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Voyager
Voyager
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Registered: ‎08-16-2018

@ssdgf 

1, 2, 3 - you copied the terminations (40R) but your routing impedance doesn't match (50R), so you may have here a source of reflections and potential problems, including currents through the protection diodes that will not only heat things up but also risk your chips. Thankfully, it's easy (ish) to replace those resistors. I'm not meaning you should do it, but check the signal integrity first, if you don't have high speed equipment, you might be able to use at a company or Uni, ask a friend... DDR3 is not rocket science today, but not a trivial thing.

4 - Sorry, I thought you were using MIG on the fabric, but you are interfacing the DDR to the PS... in that case, you still have to configure it for your DDR.

It could just be you are using the smallest package... I would say you have impedance mismatches but not so terrible for your board to be useless. Working on them could improve things, not only power but reliability and long term failures. Nevertheless, up to 85C you are safe. You can use the XADC and have it watching temperature and setting an alarm. And/or sticking a small heatsink if your height allows for that. Even without fan it can improve things.

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Newbie
Newbie
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Registered: ‎05-18-2019
 
新建位图图像.bmp
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Teacher
Teacher
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Registered: ‎07-09-2009
The more you run, the more the dissipation,,

DDR3 core is a fair amount of circuitry,
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Newbie
Newbie
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Registered: ‎05-18-2019

yes,i know the dissipation would increase as it running. but the temperature went up to over 60 degrees seems too high, is that related with the packege? my chip is only 13*13mm

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Voyager
Voyager
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Registered: ‎08-16-2018

@ssdgf 

60C, is that surface or core?

If core temp, you are still safe. Many FPGA run that hot and even closer to the limit.

Is it a custom board (I see your Mentor icon there...) or an off the shelf? I'm just thinking if you have low R's in your terminations you might have too high currents through the FPGA pins!

I have some Zynq with DDR3 and they get warm (40-50C outside), but never terribly hot. If you have lots of things running crazy then you might need heatsink and fan. Sometimes is unavoidable, but first I would discard an electrical bug.

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Teacher
Teacher
1,111 Views
Registered: ‎07-09-2009

The days of fpgas running cold are gone,

60 degrees as mentioned by others, for the silicon ( use the built in system JTAG monitor ) is fine,

       With case at 60, I'd check the silicon temprature.

 

https://www.xilinx.com/products/technology/analog-mixed-signal.html

If your driving a lot of lines fast, with littole air flow over chip, then not un expected.

 

this might help.

 

https://www.xilinx.com/support/answers/57193.html

 

 

 

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Newbie
Newbie
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Registered: ‎05-18-2019
I used JTAG to monitor the vcc and temperature, vcc are nomal. the temperature is 45C almost when ddr3 disabled, and went up to 60C in few minute once ddr3 enabled. the program running in ddr3 works fine. I pasted up the schematic and monitor picture.
新建位图图像.bmp
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Newbie
Newbie
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Registered: ‎05-18-2019
 
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Teacher
Teacher
1,068 Views
Registered: ‎07-09-2009

Whats the spec of the part your using ?

    85 degrees ?

 

looks like your well within then,

     assuming 85, and your currently at 60, your ambient can get 25 degrees hotter and you would still be OK,

 

 

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Voyager
Voyager
1,058 Views
Registered: ‎08-16-2018

I see, it's a custom board... things I would check:

- Those terminations of 40R, isn't the standard 50R? 

- Does routing match impedance?

- Are there any awful ringings in the DDR signals?

- Are FPGA DDR pins defined with the correct standard?

- Is ODT used?

- Will it be cooler at lower DDR frequencies? 

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Newbie
Newbie
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Registered: ‎05-18-2019
1.the terminations were copied from evaluation board; 2.routing match 50 impedance, and the ddr works ok, no errors in running; 3.i don't have a high speed osilator to test the ddr signal waves; 4.how to check the FPGA DDR pins's standard? it should be generated by vivado; 5.ODT is used; 6.it not be cooler at a lower frequency. 7.once DDRIOB_ADDR, DDRIOB_DATA registers's OUTPUT_EN be set to 11, the temperature goes up.
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Voyager
Voyager
1,035 Views
Registered: ‎08-16-2018

@ssdgf 

1, 2, 3 - you copied the terminations (40R) but your routing impedance doesn't match (50R), so you may have here a source of reflections and potential problems, including currents through the protection diodes that will not only heat things up but also risk your chips. Thankfully, it's easy (ish) to replace those resistors. I'm not meaning you should do it, but check the signal integrity first, if you don't have high speed equipment, you might be able to use at a company or Uni, ask a friend... DDR3 is not rocket science today, but not a trivial thing.

4 - Sorry, I thought you were using MIG on the fabric, but you are interfacing the DDR to the PS... in that case, you still have to configure it for your DDR.

It could just be you are using the smallest package... I would say you have impedance mismatches but not so terrible for your board to be useless. Working on them could improve things, not only power but reliability and long term failures. Nevertheless, up to 85C you are safe. You can use the XADC and have it watching temperature and setting an alarm. And/or sticking a small heatsink if your height allows for that. Even without fan it can improve things.

View solution in original post

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