[weinzierl]

This is a fantastic read. At the risk of being the guy that needs the joke explained, I can't make sense of following paragraph:

> While the -6 volt supply spec caused little trouble for the LM383, it meant that all the other electronics in a car needed to voltage regulator that could provide protection.

The other components need protection anyway. What is the connection to the LM383?

> Some one made the joke that the lateral PNP's were so bad that even delco would not be able to destroy them.

Why are bad lateral PNP's hard to destroy? Is he talking about PNP's inside the LM383 or inside other power supply circuitry that's supposed to provide protection?

>A skunk works layout of a lateral PNP regulator ultimately made its way to delco. And sure enough, they could not destroy it. They loved it. And National Semiconductor got into the business of making PNP output regulators.

[jjoonathan]

I think the -6V connection was simply that the LM383 designers were able to trivially integrate something the automotive industry considered non-trivial due to historical reliance on discrete processes and "build it sturdy" engineering. Nowadays chips are so highly integrated, so cheap, and so ubiquitous that it's hard to imagine dealing with messy power any other way, but it wasn't always so.

I have vague intuition that p-type silicon has lower mobility and worse ohmic-junction performance than n-type silicon. A real semiconductor engineer should verify, but I believe the core of the dig is that the low performance acts like intrinsic protection: the PNPs simply couldn't conduct enough current to destroy themselves, at least not in the multitude of spectacular fashions as the NPNs.

[mbell]

Electrons are the majority charge carriers for NPN vs holes in PNP which does mean that NPN transistors are faster, they also are usually a _bit_ better than PNP in other specs (beta, etc).

However I don't think this was the main part of the joke, rather it's that lateral transistors are _way_ worse in pretty much every conceivable metric than vertical transistors save two - they are hard to destroy and cheap. So add 'lateral' to 'PNP' and you basically have 'worst possible transistor', so bad that you can't kill it.

[jjoonathan]

Thanks for clarifying. I chalked up the difference between 'a bit' and 'can't kill it' to mitigations that have happened since the LM383 was designed but now that I'm reading up on lateral transistors it looks like you're almost certainly right.