Request for definition of "power well"

Isn't it just an odd term for a power buss?

Never heard the term.

John

Are you sure it's not a bad translation of "Power good" ?

Best regards, Spehro Pefhany

I've heard the term "voltage well" used, and it's conceivable that people might be using "power well" to refer to the same thing.

In this context, a "voltage well" is a portion of an IC (such as a CPU) in which all the logic operates from a single voltage [or a set of voltages]. A modern CPU often has several different voltage wells... for example, the CPU core may operate from 1.1 volts, while the I/O and bus pins operate from 3.3 volts. Voltage-level-shifting components are used whenever a signal must travel from one voltage well (or domain) to another.

It's not uncommon for there to be several separate voltage wells in a chip, which all use the same voltage. A "smart power" design can allow an entire well to be powered off if it's not needed, in such a way that doing so doesn't disrupt the function of other wells on the same chip (i.e. it doesn't clamp all of the shared signal lines to ground).

Powering down whole wells will eliminate the leakage current in the logic within that well, and cut power use in that well down to zero. That isn't possible if you use the older power-reduction technique (leave the logic powered up, but turn off the clock signals to it), because the very small CMOS transistors used these days do have a significant amount of leakage current (and thus power use) even if they're not being actively used.

With regard to motherboard design... motherboards for modern CPUs must generally provide DC power at several different voltages, to "feed" multiple voltage wells inside the CPU. The amount of current drawn at each voltage can vary quite a lot with time, and the changes can be quite sudden... when a CPU comes out of idle and starts processings, its current demand jumps sharply within a few nanoseconds. Designs in which parts of the CPU power up and down "on the fly" can have even more power-demand variation.

It's not an easy job for the voltage regulators.

Maybe translation? well =3D> spring :=3D=3D source, so "power source" becomes "power well"?

Maybe you are referring to the PG signal "Power Good" which is the power supply. at one time, it used to be an orange wire in the older supplies. This some times was used as part of the reset sequence on the mother board to insure the power supply was fully up and running on all of it's voltages before the CPU did a reset and to start.

Things have changed a lot over the years, it may not be what you're looking for.

P.S. The green wire is normally the ON switch that you pull to common which will turn on the supply.

No, not what I'm looking for. It's used by a major IC manufacturer, and in documentation written by US-born native English speakers, so this is not a case of Engrish poor translation.