4 ms·
Does that explain things when you're talking about a DC power supply? Isn't that what we're talking about?
by awakeasleep 11y ago
Does that explain things when you're talking about a DC power supply? Isn't that what we're talking about?
- aidenn0 11y agoDC and AC don't matter for generalities (though there are significant differences in how a given device will draw power from an AC or DC source, the underlying principle is the same). A DC power supply can still largely be modeled as a DC voltage plus some small amount of resistance, capacitance and inductance. This will give it a characteristic impedance for a short-circuit which is the only limit on how much power can be drawn from it. Aha! I found where the confusion is in this sentence: > If the charging device can use more current, nothing happens. There is no way to pull "unsupported" amounts of current out of something. This is wrong. If you draw too much current, then something bad will happen. The UL just makes sure that "something bad" isn't "will start a fire or electricute someone" it could very reasonably be a component of the DC power supply that fails with an open-circuit, which would then need replacing for the power supply to work again. In some cases it may be a part specifically designed to be a fuse, in other cases they may just take a diode, MOSFET or resistor that they needed anyway and choose a part that will die if too much current is drawn. Dell is claiming that their USB ports will not die permanently in this case, but will shut-down temporarily, more like a self-resetting circuit breaker than a fuse.