Peter,

There is a National switcher that takes +12V to 60V and supplies 5V at 3 amps. Its the LM2576HVS-5.0. There is a new product out that does this through an improved efficiency switcher but it was too new and non -45Cto+85C yet. In a year, that new product will be viable.

The problem was keeping it running with the worst-case 3 seconds of over or reverse voltages. I recommended a load dumping circuit if they wanted to spend the money and would have liked to rectified the inputs to handle the reversals but I'm a digital engineer and this is not my area of expertise.

Everytime I sketch an analog circuit, analog guys smirk (even when they later conclude its a good idea :)

Steve,

Actually, I've got a old Tandy friend that does my analog subcontracting. Its probably easy money; I've got him sanity checking our bluetooth design and making recommendations. Its not cheap, but I consider it insurance.

aka J