by Steve Anderson » Tue Nov 08, 2022 6:14 pm
Klaas, I'll take your original sentence and modify it slightly...changes in blue..."Supply voltages should never have to be more precise than +/- 0.5 volt. If your application doesn't work at that voltage, something else is faulty."...maybe not faulty, but a poor design.
Now, there is a historical exception to this - the original TTL (74xx series) which was specified from 4.75V to 5.25V. Later versions (74HCxxx for example) quite happily operate from 2-6V, though as expected at lower voltages the speed is limited. That depends on the application.
More often that not, using a regulator in a power supply isn't so much a voltage sensitivity/accuracy issue, but of hum/ripple elimination. Often adding a regulator which should mop-up any residual ripple in the power supply is cheaper and smaller than a larger capacitor. The regulation it provides is a bonus, most often it isn't required.
However the ripple rejection of most op-amps (delving into the analogue world here) is so high these days even that is a moot point. As ever, it depends on the application. You wouldn't want a volt of ripple on the supply for a microphone pre-amp for example. A 40W power amp, no issue.
Steve A.