Chip operating temperatures

[Brian Warburton, c/o Turbo Systems Ltd]

>        It does not usually get much over +40C here so the top end of the
>temp range is not much of a concern. BUT, winter IS comming. It is already
>going down to +3C at night, and -40C is not that unusual.
>
>        Wayne ( I really need to find a more moderate climate ) Braun
>Wayne Braun     Product Support Services       Develcon Electronics

Although ambient might rarely reach 40 degC, I would imagine that
the temperature inside your ECU box/enclosure is well over that.
Just think of the power dissipation from four coil drivers at say
40% dutycycle at 6000 rpm (dwell = 4mS/Wasted-Spark) and say eight
injector drivers at 75% dutycycle at 6000 rpm (Fuel p/w = 15mS/SEFI)
Typically, a 4 cylinder ECU can be sucking up to 10 Amps when the
engine's really revving, I don't have figures to hand for 8 cylinder
systems and of course all these figures depend on coil/injector type
and so on, but we're still talking about passing a lot of current
through the system. 120 watts can have pretty serious heating effects
on the box especially if it's mounted in an area of static airflow.

I would suggest that you would be advised to only use Industrial or
Automotive spec parts where available, especially if your car's
intended for serious day-to-day use. 

Failing that, mounting the ECU in the A/C outlet trunking might
prove advantageous ... :^) 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian Warburton,   "Still searching for the perfect curve....."
email: bwarb at turbo.win-uk.net
                               Advanced Automotive Electronics Ltd,
                               Van-Nuys House, Scotlands Drive,
                               Farnham Common, England.  SL2-3ES
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