Running Prop-2 with 24V power supply

[mmahrle]

I've been doing embedded programming for 30+ years, but I'm pretty new with the Prop-2.  I want to run it with 24V DC, mainly because I want to power and control a light bar that reequires 24V.  When I use a 24V supply, the voltage regulator (LM2940) gets very hot, even with no external connections (i.e. only the Prop-2 board itself.  The specs for the LM2940 indicate that it shouldn't be a problem to use a 24V input, but the regulator gets too hot to comfortably touch.  Is that normal?

[livinlowe]

It's probably OK, going from 24V down to 5V is alot of power

[mmahrle]

Thanks.  I knew that it was going to have to dissipate quite a bit to down-convert by ~19V, but I just wanted to make sure there wasn't someting wrong with this Prop-2.

It's got a Parallax RFID reader and an RC-4 to control the light bar (which is being powered by the 24V as well) hanging off of it.  It's been running fine, although warm, for the last 4 hours so I guess everything's ok.

[JonnyMac]

We selected the LM2940 because it can take it.  I've designed it into industrial products that also operate at 24v with no problems.