Re: 2 leg crystal on FPGA: Lattice vs Xilinx

On 29 Sep., 09:29, hal-use...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (Hal
Murray) wrote:
I have submitted this idea (at least 1 DCM with pins for crystal) many
years ago.

I assume Xilinx marketing is smart enough to analyze the tradeoffs.

I remember being grumpy that the 2 special IOBs on the 3000 series
chips were slightly different. I don't remember the details, it
was probably something like slightly slower or a few extra pF.
It wasn't a big deal, at least most of the time, but it was
one more thing you had to keep in mind.

Southbridge chips often contain the RTC and whatever it takes
to drive a 32 KHz crystal. I haven't looked carefully, but I
haven't seen one that includes the magic PLL clock generator
stuff. That seems like a very tempting target for high volume
cost sensitive applications so I assume there is a good reason
they don't do it.

--

well, is that the same reason why Actel _INCLUDED_ oscillator in the
Fusion :) ?

Antti




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