| ▲ | analog31 3 hours ago | |
At least going between 3.3 and 5 Volts, they depend on the fab process used to make the chip. Fab capacity is more widely available for the lower voltages, making it inconvenient to keep supplying higher voltage chips. It has also gotten easier to do high performance analog at lower voltages. Yeah, it's a pain. Many of my boards have both 3.3 and 5 Volt rails. There are quite a number of level-shifting logic buffers, for instance that are powered by 3.3 but accept 5-V inputs with no penalty. For hobbyist type stuff, a 3.3 V CMOS chip will accept a 5 V logic signal if you feed it through a series resistor, since the built-in protection diodes of the CMOS chip will clamp the voltage. Don't let the engineers catch you doing it. ;-) But I often use a series resistor to provide a little bit of overload protection to a CMOS input. Little or no logic ever operated at 24 V, other than relays. There's always some level translation needed there. The higher voltage follows the same rule as electric transmission lines: Correspondingly lower current allows for thinner wire, of importance if you're driving something like a solenoid valve. | ||