When repairing or maintaining equipment, or even during design revisions, why would I, for electrical reasons (not interested in the potential financial aspects) not want to replace a PN junction with a Schottky diode? Three reasons I can come up with:
- Leakage: Schottky diodes have, in general, larger leakage
- Biasing: If the PN junction is used to bias other devices (such as is sometimes done in BJT output Class AB amplifiers)
- Switching applications: We might desire to use the slow reverse-recovery in RF switches.
Are there any others? In my specific case, I am replacing diodes in a older HP 6253A powersupply. The powersupply has several 3A rated PN junctions in the signal path which look very corroded, and I have a number of 6A Schottky diodes I am looking to replace them with. Is there any reason why I wouldn't want to do so?
Best Answer
While Schottky diodes generally have a lower forward voltage drop and faster recovery time, they are also more susceptible to reverse surges. In my experience a Schottky diode will fail at a lower reverse voltage (or during a transient) that a standard silicon diode would handle without a problem. It all comes down to your application, what the diode is doing, and what sort of electrical events you expect it to see. There is no right or wrong answer here.