Author Topic: 4 Layer Board for ZYNQ and DDR3  (Read 10966 times)

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Offline OwO

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Re: 4 Layer Board for ZYNQ and DDR3
« Reply #25 on: March 04, 2020, 02:44:47 pm »
Yes, also the Zynq-7020 will need to be heatsinked too. On a Zynq-7010 with a almost fully loaded design drawing under 2A total (Vccint and Vccintp combined), it easily reaches 85C junction temperature. Zynq-7020 can draw as much power as an Artix-100T (~6A on Vccint under full load). What I did in sdr5 is put all higher profile parts on the opposite side as the Zynq, and use thin thermal pads to heatsink the Zynq to an aluminum plate/enclosure.
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Online asmi

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Re: 4 Layer Board for ZYNQ and DDR3
« Reply #26 on: March 04, 2020, 03:03:06 pm »
I found an easy way to seriously heat up any 7 series FPGA - just overclock their BUFGs, load design into FPGA and watch Tj skyrocket! Even A35T will get 70°C+ without heatsink if I run my 1080p HDMI out design (which overclocks a single BUFG to 742.5 MHz that's specced to 628 MHz for -2 speed grade), and the S50 chip from the board in my signature get into 60°C+ even with a small heatsink (without it the chip went into 90°C+ before I intervened to reset the design).
Part of the reason is that these boards are quite small, so FPGA can't sink a lot of heat into the board (The Rtjb of FTG-style packages is a lot smaller than Rtja), especially when it has to "compete" with DC-DC converters which also sink heat into the board.
« Last Edit: March 04, 2020, 03:15:19 pm by asmi »
 

Offline aseok

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Re: 4 Layer Board for ZYNQ and DDR3
« Reply #27 on: March 07, 2020, 06:18:01 am »
What is the dram data and address bus termination configuration?
 

Online KE5FX

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Re: 4 Layer Board for ZYNQ and DDR3
« Reply #28 on: March 07, 2020, 08:36:08 am »
I found an easy way to seriously heat up any 7 series FPGA - just overclock their BUFGs, load design into FPGA and watch Tj skyrocket! Even A35T will get 70°C+ without heatsink if I run my 1080p HDMI out design (which overclocks a single BUFG to 742.5 MHz that's specced to 628 MHz for -2 speed grade), and the S50 chip from the board in my signature get into 60°C+ even with a small heatsink (without it the chip went into 90°C+ before I intervened to reset the design).
Part of the reason is that these boards are quite small, so FPGA can't sink a lot of heat into the board (The Rtjb of FTG-style packages is a lot smaller than Rtja), especially when it has to "compete" with DC-DC converters which also sink heat into the board.

Meh, 70C is barely warmed up. :)  You can get them rated for 100C.

I don't know if you're using the internal XADC-based thermometer to check the temperature, but something I've noticed is that it overreports the temperature by anywhere from 5-10C.  You can verify this simply by checking it immediately after power-on, when the die is still at room temperature.  In a 25C environment it's not uncommon to see 30-32C reported, and I doubt it's any more accurate at higher temps.

So you are probably fine at 70C indicated, at least IMHO.
 

Offline OwO

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Re: 4 Layer Board for ZYNQ and DDR3
« Reply #29 on: March 07, 2020, 08:37:12 am »
Address/control are source terminated only, by FPGA driver impedance. Data lines use on-chip termination (source and load) which is standard in DDR3 and later. It's not possible to fit termination resistors on the PCB and maintain ground integrity.
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Offline ali_asadzadehTopic starter

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Re: 4 Layer Board for ZYNQ and DDR3
« Reply #30 on: March 16, 2020, 07:44:41 am »
what'a the part number of your DDR3 parts?
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Offline OwO

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Re: 4 Layer Board for ZYNQ and DDR3
« Reply #31 on: March 16, 2020, 08:29:40 am »
H5TQ4G63AFR is what I used on that board and seems to be the most common DDR3 component on the market.
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