dc42: I think your schematic is not quite right. According to the datasheet, the input supply should go to pin 6, not pins 1/7/8.
You're right... the supply should connect on the pin 6 side of R2, not the pin 7/8 side. Thanks for catching that! :-)
dc42: R1 is too high. At 1A output, the input current will be around 0.7A at 10v input, and a 10 ohm resistor will drop 7v.
I don't understand -- how's it dropping voltage? Unless the TVS is clamping there's no voltage divider, and it should only act as a current limiter. What did I miss?
dc42: I'm not sure you should worry about a 24v jump start, you will have other things to worry about (like the 12v vehicle battery exploding).
I've heard of people doing this, but TBH, I have no idea if it's safe at all. Batteries are more complicated than my simplistic understanding of them, so I tried to accommodate this technique if or when it's used. I certainly wouldn't do it, as I don't have the prettiest face in the world, but I'd still like to keep it. Maybe it's safe enough for short periods. I'll leave that to the professionals, and try to build a PSU that can keep up.
dc42: I wouldn't use a bridge rectifier on the input, you already have a protection diode and if you are going to use mosfets to switch anything running from the 12v supply, you will need a common ground anyway.
Yeah, I'm leaning that way. I do like the idea in theory, so I may provide it as an optional alternative with caveats. BUT, having the PSU cheerfully cope with reverse connection, and then having the load self-destruct when it connects to external circuits is not exactly my idea of friendly, nor easy-to-use, so I think I'll design for one-way operation by default.