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Re: Automotive temp MCU
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They can be parked/stuck in a tunnel for hours.  


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Yes, I am doing that with the LDO.  But I prefer to use fully spec'd
automotive parts.  I have found a number of PICs that can do
automotive.  Now I am just trying to optimize my choice.  


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This MCU will be dissipating nearly no power (uWs) when over 85C.  So I
don't think this is needed.  

 
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This part is on the bottom of the board with 0.1" clearance, not much
room for a heatsink  :)


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Far too exotic, but thanks for the suggestions.

Re: Automotive temp MCU
Microchip's sampling is very generous! I've gotten at least 5
different mcu samples. They ship it to you in less than a week, direct
from Thailand or something like that.




snipped-for-privacy@ieee.org (Rob Young) wrote in message
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Re: Automotive temp MCU
hi, 125deg used to be the military grade, have things changed while I wasn't
looking? Can't you get away with 85deg?

Re: Automotive temp MCU
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Mil temp is *-55C* to +125C while automotive (or Microchip calls it
"extended") is *-40C* to +125C.  

I am building a board that will run at up to 85C, but it will shut
itself off at 85C and survive up to 125C.  The part that controls the
on/off (which also includes a low power mode with multiple wake up
options) is simplest if I use a small MCU.  If I use other,
non-programmable parts, I end up with several devices to replace the
MCU.  By adding the MCU I also get several other features that otherwise
need even more chips.

Re: Automotive temp MCU
writes

[snip]

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An 85C PIC will easily run at well over 125C - just don't use the
internal RC oscillator or watchdog.  Are 125C rated parts any different?
Don't think so.  Try it.

--
Syd


Re: Automotive temp MCU
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Yes, they are different, they are guaranteed to meet spec at 125C if
nothing else.  I can't come close to testing the parts the way the maker
does.  Some things like leakage current are important and not worth
testing on chips before I make the boards.  I have considered building
the boards with industrial chips and testing each one, but this can be
very expensive.  

Thanks for the suggestion anyway.

Re: Automotive temp MCU
writes
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Just words.  Words which may be important, depending on liability, but
that's not for me to judge.  So you get one of these parts which is
guaranteed to work at 125C and it fails... Money back?

Fact is, the 85C parts will work, but it's then *your* responsibility.

--
Syd


Re: Automotive temp MCU
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*Now* you understand...

Its also marketing.  Selling a board for 125C operation and using chips
clearly marked for 85C that control power to the rest of the board can
be hard to explain.  I'd rather let my customers have confidence in the
chips that I pick rather than asking them to have confidence in me (an
unknown to many of them).

Re: Automotive temp MCU

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Have a look at the ST6 series from ST http://www.st.com/

They may do what you want but the temp range is only -40
to +85.  Something like the ST6265 has 21 i/o, 3884 byte
user ROM, 128 bytes RAM, 128 bytes EEPROM. 8 i/o can drive
20mA, 8 can be ADC input, any digital i/o can be used for
interrupt.  Has other "nice" features as well - but it is
slow nowadays - 8MHz crystal divided by 12/13 for internal
clocks.

Alan

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P O Box 1108, Morley, WA, 6943
Tel: +61 8 9370 5533 Fax +61 8 9370 5106
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Re: Automotive temp MCU
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Thanks for the reply, but the temperature is what this question is all
about.  I can find lots of chips that meet all the other requirements
including the tiny QFN package and the low price.  

I can also find parts that are automotive temp, but they fail in one of
the other requirements.  I found one that is only slightly out of my
price range and is about twice as large as a 28QFN.  So I can use it if
I have to.  I am just trying to cover all the ground to make sure I have
not missed anything.  

Too bad Atmel does not have an automotive temp AVRs.  I would love to
use one of them.

Re: Automotive temp MCU



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Take a look at the Zilog eZ8 family ?

If you like the AVRs, imagine adding a register Frame pointer, and
some efficent direct memory opcodes, and you are close to a Z8

eZ8's come in extended temp (-40'C to 105'C), which is a gain on your
"sleep above 85'C" - they start at SSOP20, and go up to 80 pins.

  System wise, I'd design in as much thermal inertia as possible,
get power-paranoid to reduce the self-heating, and record/log
the actual temperatures, as well as do a memory checksum and train (sic)
the customers they need to replace your modules after so many LogT *
Hours product.

-jg




Re: Automotive temp MCU
oN 27-Jan-04, Jim Granville said:

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I used to be a Z8 fan, but the brain-damaged implementation of a UART was =
a serious impediment. Did that get fixed on the way to the eZ8?

The Super8 was a much better device, but they shot that one out from under =
us a few years ago, and with almost no advance notice. That left me little =
confidence in Zilog as a supplier.

--
Bill
Posted with XanaNews Version 1.16.1.4

Re: Automotive temp MCU

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serious impediment.
 > Did that get fixed on the way to the eZ8?

  The eZ8 UART looks at the top end of uC uarts - it has TX Shift and TX
hold  empty, as well as CTS hardware flow control, and parity/address
recognize/BRG/Break , and IRDA pulse modes too..


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a few years ago,
 > and with almost no advance notice. That left me little confidence in
Zilog as a supplier.

  Technically, one might have expected the FLASH devices to choose the
Super8, but I guess commercial reality hit, and they decided to just do
OTP -> FLASH on a family that has some market coverage.

-jg


Re: Automotive temp MCU

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I think that you can get some Atmel Flash 8051s (at least the T89C51CC01 CAN
version)
in full Automotive temp but I do not have the full list.
Check with your local Atmel FAE.

--
Best Regards
Ulf at atmel dot com
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Re: Automotive temp MCU
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I sent an email to Dan Ujvari, but I have not received a reply.  Of the
8051s I saw on the Atmel site, they were not very well suited to this
app.

Re: Automotive temp MCU
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  Since this chestnut is a common one, I did see Atmel have
posted new data on their ATAM893-J
  http://www.atmel.com/dyn/general/tech_doc.asp?doc_id75%29

This has both wide Vcc (1.8-6.5V) and Wide Temp (-40'C..+125'C)
and good low power operations of 32Khz clock engine (< 1uA).
  Would make a good extremes system power sequencer / wdog /
general health monitor...
-jg


Re: Automotive temp MCU
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The AT89C51CC01 is also coming in Automotive temp.


--
Best Regards
Ulf at atmel dot com
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Re: Automotive temp MCU
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This is of interest to me.  I looked at this data sheet and could not
find any significant differences to the ATAM893-V.  Both are wide temp
and the rest seems to be the same except for notes about how the -J
version has a 5% faster clock (on the average) compared to the ROM parts
and the -J version the lack of selectable high drive outputs on the -J
version, again compared to the ROM versions, not the -V.  

Anyone see a significant difference between the -J and the -V versions?
Did I miss something big?  

--

Rick "rickman" Collins

snipped-for-privacy@XYarius.com
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