Diodes – What Do You Need To Know

Diodes are available in different sizes and shapes. High-current diodes are usually mounted on a heat-sink device that helps reduce their operating temperature. It is very much possible to place diodes in parallel to enhance their current-carrying capacity. However, the VI traits of both diodes must closely match to make sure that the current divides evenly (though a small resistor needs to be placed in series with each diode that helps equalize the currents). All diodes come with a leakage current.

The leakage current is also called as the reverse current. This is quite small, usually within the nano ampere range. Diodes also support a maximum allowable reverse voltage, peak inverse voltage (PIV), peak reverse voltage (PRV), above which a large amount of current flows in the wrong direction. In case the PIV exceeds, the diode may be zapped and might be permanently damaged. The PIV for diodes varies from a few volts to as much as more than a few thousand volts. One technique for achieving an effectively higher PIV is to keep diodes in series. Again, it is imperative that the diodes must match. This ensures that the reverse voltage divides equally. Though a small resistor placed parallel with each diode can be useful in equalizing the reverse voltages. Learn more at

One other aspect to consider here about diodes include the capacitance (formed across the pn junction), maximum forward current (IF), along with reverse recovery time. Most diodes have a 1-prefix designation. The two different ends of the diodes are generally differentiated from one another by a mark. For glass-encapsulated diodes, a cathode is designed using a black band. The black-plastic encapsulated diodes, on the other hand, use a white band. If there are no symbols, as there are some with power diodes, the cathode perhaps be a bolt sort of piece. This piece is the one inserted through a heat-sinking device and is fastened down using a nut. A mica or fiber washer is useful in isolating the cathode electrically from the metal heat sink, and specially designed silicone grease is placed between the heat sink and washer to boost thermal conductivity.

A zener diode, however, is a device that works as a usual pn-junction diode when it comes along to forward biasing, but also holds the trait that helps conduct in the reverse-biased direction in case a certain breakdown voltage point is reached. The Zener diodes generally have breakdown voltages in the range of a few volts to 100 volts.

  • Love
  • Save
    Add a blog to Bloglovin’
    Enter the full blog address (e.g.
    We're working on your request. This will take just a minute...