View Single Post
Old 06-16-2008, 02:27 PM   #16 (permalink)
ConnClark's Avatar
Join Date: Jun 2008
Location: Richland,WA
Posts: 984

Das Schlepper Frog - '85 Mercedes Benz 300SD
90 day: 23.23 mpg (US)

Gentoo320 - '04 Mercedes C320 4Matic
90 day: 22.44 mpg (US)
Thanks: 46
Thanked 230 Times in 159 Posts
Originally Posted by MilesPerTank View Post

Max junction is 125C with a RthetaJA of 65 C/W. Using the above 1.8W*65C/W = 117 C. You can see if our 200mA is correct we are already in violation of the max temp even under a 25C air conditioned lab when using the cars voltage range. Anyone got some good temperature probes at home to mount to one of these? I'll take the board into work tomorrow and try to get some load current measurements.

I plan to mount a nice sized power resistor in front of the 7805. It will help current limit and burn some of the initial 14V .
We are supposed to be saving energy here ;-)

Here is a Switching 7805 drop in replacement project

Also for an OpenSource layout and schematic program look at kicad. It supports Linux/Unix and windows.
  Reply With Quote