[londons_explore]

Why don't all silicon chips have glitch and overvoltage detection?

It would seem very easy to put a pair of fets in such a way they detected sudden voltage changes (via their gate capacitance). That could then be used as an input to a circuit which ensured the chip is properly reset by asserting the reset line for at least 1 clock cycle.

This should probably be paired with brown-out detection, although that's power hungry, so I can see why people might not want it.

This wouldn't only have security benefits - lots of electronic designs might be accidentally glitching their microcontrollers due to poor design of other circuits, and having the chip reset in a predictable way is much better than undefined behaviour.

[pjc50]

Brownout detection is definitely one of those things to turn off for low-power operation. I suspect glitch detection is harder than it sounds, too.

[sschueller]

Probably due to price. Some applications it doesnt matter if the chip can be glitched but getting them at a lower cost does matter.

[skunkpocalypse]

> Why don't all silicon chips have glitch and overvoltage detection?

Reliability. This is basically the microchip version of Boeing's MCAS.

The circuit you describe is not only an analog circuit, but is in fact a noise amplifier. You're now shipping a chip containing a noise amplifier that drives the device-wide reset line.

What could go wrong?

The stuff you describe is very, very difficult to get right, and beast-mode insanely difficult to troubleshoot or even diagnose when it goes wrong.

It's also very sensitive to manufacturing variations. So if there is a problem with the circuit, it'll probably only affect a few batches. Which, Murphy's Law and all, will be the batches that wind up in the hands of your most important customers.

Stuff like this can bankrupt a chip company if you get it wrong, and there's no way to be sure you got it right. At most you put it in your super-high-end ultra-secure product line, so long as that line's sales are small enough that you can afford a recall.