RE: MPC555 Temperature Sensitivity?

you probably have floating pins. revision M fixes an errata that some of
the internal "weak" pullups were not actually disabled when you disable
(SPRDS) them in the PDMCR register. Now that they are always disabled
when you disable them. The MPC555 Reference Manual states that these
pins must have external pull ups. The weak pull ups are not strong
enough to be relied on in a system over temperature.
 
BG, BB, BR, are the primary pins that cause issues in customers targets,
but bi_b_sts_b, burst_b, bdip_b, ta_b, ts_b, tsiz1, tsiz0, tea_b,
rd_wr_b, br_b_vf1_iwp2, bg_b_vf0_iwp0, bb_b_vf2_iwp3 are all of the pins
that that the pull ups are now really disabled by SPRDS (like they were
supposed to be).
 
randy
 

	-----Original Message-----
	From: [email protected] [mailto:[email protected]] On
Behalf Of trailrunner23
	
	

	Hello All,
	
	I asked a question recently about problems we're having, and I
have
	more information. We have two different MPC555 part numbers:
	
	MPC555LFMZP40 (-40 to +125)
	MPC555LFCZP40 (-40 to +85)
	
	Both of these are "K3" parts (IMMR = 0x3032).
	
	The problem we're having is that our boards with M parts are
getting
	Machine Check Exceptions when our enclosure gets warm, but we're
	talking about 50-55C, nowhere near the ratings, and it seems to
be a
	problem on the M parts, which are supposed to tolerate very high
	temperatures.

	.
	
<http://geo.yahoo.com/serv?s=97359714&grpId=6276387&grpspId=1601554205&m
sgId=3638&stime=1150858009> 
	 



[Non-text portions of this message have been removed]



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