Overclocking the Motorola 860 family

[Dan Malek]

Conn Clark wrote:


> 	Has anybody overclocked a MPC860 or a MPC850?

I've tried cranking up the PLLs beyond the chip spec.  None of them
have ever worked.  I could only get 4 MHz steps, so I tried the 80 MHz
at 84MHz, which didn't work (including all UPM timing changes to ensure
memory was OK).  Maybe it would run at 81 or 82 MHz....

> .... Right now we run our 850 at
> 49.1MHz and I want to double it.

No way.  I've tried lots of different speed spec parts at higher than
rated values, none has ever worked for me.  It appears Motorola has a
pretty good screening process, and when they state 50 MHz it isn't likely
to run beyond that.  Even if one appears to work, I wouldn't expect a
product or volume manufacturing to be successful.


	-- Dan


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