Author Topic: Is there any bigger 5V or 5V-tolerant FPGA?  (Read 1088 times)

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Online technix

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Re: Is there any bigger 5V or 5V-tolerant FPGA?
« Reply #25 on: October 18, 2018, 08:15:34 pm »
I think I found a way out of this on 68010: that chip, while requires 5V operation, is capped at 2.4V VOH. So maybe just put a 510 ohm series resistor in there to soften the glitches if there is any and just wire that directly into the 3.3V system as-is.
 

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Re: Is there any bigger 5V or 5V-tolerant FPGA?
« Reply #26 on: October 18, 2018, 11:09:57 pm »
Today I am with a customer, and I have just seen a development Spartan2 board in their lab. It's was manufactured by Avnet, and the PCB is six layers  :o :o :o

Talking with their PCB-skilled guys confirmed my doubt: for a large FPGA with a lot of chip on the PCB, you have to go for 4 layers for signals and 2 layers for the power distribution, this, plus a lot of decoupling  :o  :o :o

the Bunker is open!
 

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Re: Is there any bigger 5V or 5V-tolerant FPGA?
« Reply #27 on: October 18, 2018, 11:24:16 pm »
Today I am with a customer, and I have just seen a development Spartan2 board in their lab. It's was manufactured by Avnet, and the PCB is six layers  :o :o :o

Talking with their PCB-skilled guys confirmed my doubt: for a large FPGA with a lot of chip on the PCB, you have to go for 4 layers for signals and 2 layers for the power distribution, this, plus a lot of decoupling  :o  :o :o
Maybe I am a signal contortionist, but I usually get it done within 4 layers. That point to point DDR3 bus of A13 is a single layer job for me, for example. I abuse and overuse pin swapping.

Even the power planes can be pretty contorted and I love scattering local regulators all around the main chips. That same A13 board has a TPS562200 right next to it as the memory VDD local regulator.
 

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Re: Is there any bigger 5V or 5V-tolerant FPGA?
« Reply #28 on: October 18, 2018, 11:41:55 pm »
bah, I doubt ... anyway, which EDA software do you use?
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Online technix

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Re: Is there any bigger 5V or 5V-tolerant FPGA?
« Reply #29 on: October 19, 2018, 12:10:02 am »
bah, I doubt ... anyway, which EDA software do you use?
KiCad. That is why I was complaining about it lagging on my machines back then.
 


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