Thursday, March 28, 2019

Things to Know About Diodes

Diodes come in many shapes and sizes. High-current diodes are often mounted on a heat-sink device to reduce their operating temperature. It is possible to place diodes in parallel to increase the current-carrying capacity, but the VI characteristics of both diodes must be closely matched to ensure that current divides evenly (although a small resistor can be placed in series with each diode to help equalize the currents. All diodes have some leakage current (current that gets through when a diode is reverse-biased).

This leakage current-better known as the reverse current (IR) -is very small, typically within the nano ampere range. Diodes also have a maximum allowable reverse voltage, peak reverse voltage (PRV), or peak inverse voltage (PIV), above which a large current will flow in the wrong direction. If the PIV is excluded, the diode may get zapped and may become permanently damaged. The PIV for diodes variates from a few volts to as much as several thousand volts. One method for achieving an effectively higher PIV is to place diodes in series. Again, it is important that diodes are matched to ensure that the reverse voltage divides evenly (although a small resistor placed in parallel with each diode can be used to equalize the reverse voltages).

Other things to consider about diodes include maximum forward current (IF), capacitance (formed across the pn junction), and reverse recovery time. Most diodes have a 1-prefix design (eg, 1N4003). The two ends of a diode are usually distinguished from each other by a mark. For glass-encapsulated diodes, the cathode is designated with a black band, whereas black-plastic encapsulated diodes use a white band. If no symbols are present (as seen with many power diodes), the cathode may be a bolt like piece. This piece is inserted through a heat-sink device (piece of metal with a hole) and is fastened down by a nut. A fiber or mica washer is used to isolate the cathode electrically from the metal heat sink, and a special silicone grease is placed between the washer and heat sink to enhance thermal conductivity.

A zener diode is a device that acts as a typical pn-junction diode when it comes to forward biasing, but it also has the ability to conduct in the reverse-biased direction when a specific breakout voltage (VB) is reached. Zener diodes typically have breakdown voltages in the range of a few volts to a few hundred volts (although larger effective breakdown voltages can be reached by placing zener diodes in series).












  • When a Man is Distant After Sex - Why This Happens and How to Change ItWhen a man is distant after sex, it leaves the woman he's involved with full of questions. She wonders what's going on and what exactly she did wrong. In most cases, if she tries to talk to him about it, he'll act surprised or say he has no idea…
  • Big Thanks to Cement Manufacturers for Promoting Green Environment With the alarming situation of global warming, people are becoming more conscious about the environment. They are continuously pursuing for producing the green products in every industry. Like many other industries, the cement industry is also…
  • Technology What is technology? I bet that everyone you ask will give you a different definition, depending on the things he / she uses. I'm sure your mother will tell you that technology makes her life easy because of all the gadgets that were…
  • Make Extra Money With Microstock If you are a freelance designer, illustrator or photographer, you may have gotten to the stage where you are a bit fed up with swapping all your time for money. If that's the case, then how do you supplement your income from work with extra…
  • Your Ultimate Guide to Choosing Duffel Bags There are several types of bags available in the market, and one of the most popular types is the duffel bag. The bag's name came from the Belgian town of Duffel, where the material used to make the original version of this kind of bag came…