Just to clarify this further.....I emailed Microchip tech support about this
issue yesterday.  Here is the email dialog:

ME:
"I am confused about the maximum speed the PIC18F6270 can run at. The
website says 25mhz, but the datasheet says it can run 10mhz with HS-PLL for
40mhz operation.  There is no mention of this in the erratta.  Or is there a
25mhz version and 40mhz version of the chip?? So...what is it?  25mhz or
40mhz?"

MICROCHIP:
"The PIC18F6720 can operate up to 25MHz. Please see Figure 26-3 in the data
sheet (DS39609A) for the voltage-frequency graph. The PLL is designed to
generate a 40MHz signal but the part cannot operate at this speed. Other
PIC18 parts such as the PIC18F6520 and PIC18F6621 can run at 40MHz."

ME:
"Hmmm....Unfortunately, those chips have less than 1/2 as much memory, and
my application won't fit on them. Do you have any plans to release an 18
series chip with 128k of memory,
and that can run at 40mhz?"

MICROCHIP:
"We do plan to release a faster 128kB part, but not in the near future."

Conclusion:

So, Microchip does not make any PIC right now with 128k, that can run at
40mhz (running in-spec of-course).  They apparently have plans for it in the
future....but it doesn't exist today.  The datasheet is just plain wrong.  I
will probably go with a 64k, 40mhz,  TQFP part for now, and then upgrade
later when a 128k one becomes available.

Hope this helps clarify things,

- Ted



-----Original Message-----
From: Ken Pergola [mailto:no_spam@LOCALNET.COM]
Sent: Wednesday, December 10, 2003 9:42 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC:] Bootloader on a 18Fxxx?


George Tyler wrote:

> You mean I'm using it out of spec?!

Hi George,

If you are running a PIC18F8720/8620/6720/6620 greater than 25 MHz, then you
are running it out of specification.
Just look at the PIC18F6620/6720/8620/8720 VOLTAGE-FREQUENCY GRAPH in the
erratas (DS80172A, DS80129G).

I think this issue caught a lot of people off guard. The current data sheet
for the PIC18F8720/8620/6720/6620 devices states Fosc max of 40 MHz, but the
Fosc max has been down-graded in the errata which states 25 MHz Fosc max.

You might want to contact Microchip sales to get more info on this issue.

Hope this helps.

Best regards,

Ken Pergola

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