[time-nuts] Divide by five

[Bob Camp]

Hi


> On Nov 8, 2014, at 7:14 PM, cfo <xnews5 at luna.dyndns.dk> wrote:
> 
> On Sat, 08 Nov 2014 18:17:09 -0500, Bob Camp wrote:
> 
>> Hi
>> 
>> I’ve done a lot of designs with Altera parts. They are fine parts, but
>> they are not magic. 
> 
> SNIP
> 
> The Cyclone 2’s had a minimum rated PLL
>> input of 20(?) MHz. The later parts bumped that down to 10 MHz. Much
>> more TimeNuts compatible.
>> 
>> Bob
>> 
> 
> Bob
> 
> Hmmm ...
> 
> I didn't know the CycloneII had a Min of 20Mhz.
> Is that in some doc you can point me to ?
> 
> Well it seems to be 11Mhz for the CycloneII ... (Bummer from a T-Nut 
> perspective)
> http://tinyurl.com/opvng2y
> 
> 
> I just tried to do a 10 => 100Mhz PLL in the EP2C5T144C8 , using the 
> "MegaWizzard" , and there were no errors or warnings.
> 
> Strange if the Min input is 11Mhz 

Back when they were new, I think the limit was higher than that. I suspect the simple answer is “does not work reliably at 10 MHz over all voltages and temperatures”. I haven’t done a Cyclone II design in many years. It’s been almost that long since I looked at a Cy II spec sheet. 

Bob

> 
> Anyways , thanx for enlighten me Bob.
> 
> CFO
> 
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