Real Diodes
2. Acknowledging the Differences
Okay, so ideal diodes don’t dissipate power. Great! But we don’t use ideal diodes in actual circuits, do we? We use real diodes, the ones with all their quirks and imperfections. And yes, real diodes do dissipate power. The difference lies in their, shall we say, less-than-ideal characteristics.
Real diodes have a forward voltage drop. This means that when they’re conducting, they require a certain voltage to be present before they really start letting current through. Think of it like needing to pay a small toll on that electron superhighway. This voltage drop, typically around 0.7V for silicon diodes, is where the power dissipation comes in. Because theres both voltage and current, theres power being converted to heat, though generally less than other components.
Furthermore, real diodes have some leakage current in the reverse-biased state. It’s a tiny amount, like a microscopic crack in that impenetrable wall, but some current does manage to trickle through. And even a tiny current at a significant reverse voltage means some power dissipation, however minimal it may be. Its like a very slow leak that will eventually fill the bucket, if you let it continue for an infinite amount of time.
The amount of power a real diode dissipates depends on several factors, including the forward current, the forward voltage drop, the reverse voltage, and the reverse leakage current. Datasheets for diodes provide this information, allowing engineers to calculate the expected power dissipation and ensure that the diode doesn’t overheat and fail. We need to consider the total load, power, and other things related to voltage. Real life is messy!