という問題が存在する。
以下のメールのやりとりを参照。
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Subject: Re: Fw: AT94K40AL-25BQC Doesn't work 24.576MHz OSC
Date: Mon, 9 Dec 2002 13:35:00 -0500 (EST)
From: xxxx <xxxxx@atmel.com>
To: Lasa@xxxx.or.jp
Hello Lasa,
We have recently recognized operating performance issues with AT94K40AL
device which relate back to the problem you are seeing.
We are working toward a solution, however in the meantime, the best workaround
is to use a crystal or oscillator frequency of 18Mhz or less.
The FPGA core is not limited to this restriction.
You have noted being able to run at up to 20Mhz, however the
recommended 18Mhz. cutoff previously mentioned takes into consideration
worst case operating voltage, temperature and process.
If your application must run at 25Mhz, then you may want to consider
the use of AT94K10AL or AT94K05AL devices, assumiing your FPGA logic will
fit into their smaller arrays.
We apologize for the inconvienence and hope one of the alternate solutions
mentioned will work for you. I expect an eratta document will be posted
on our web-site in a few weeks with more details on the final resolution.
Please contact me if you have further quesitons.
Best Regards,
___________________________________________________________________
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