Testing Schottky Diode

Schottky diodes or schottky barrier rectifier are designed for high efficiency rectification purposes essential for applications like switched mode power supplies (SMPS), switching regulator and many other power circuit. If you read the electronic schematic diagrams, schottky diodes symbol looks the same as the normal diode, even the shape and outlook just like a normal diode. The major differences between a normal diode and a schottky diode is the code or part number printed on its body. Due to this, many engineers and technicians thinks that testing a schottky diode is just the same as testing a normal diode. Infact there is a accurate method to identify schottky diode and a suggested right way to check it. Searching the internet at google search engine for the diode schottky part number and browsing through the semiconductor data book can quickly give you the answer whether the component that you are checking is a normal diode, ultra fast recovery diode or schottky diodes. If you have confirmed that the diode is a schottky diode then you have to use the right way to test it which i' m going to explain to you below.

Set your analogue multimeter to the range of times 10kohm. Put the red probe to the cathode and the black probe to the anode. You should see the pointer goes up to full scale which is zero ohms. Reversing the probe will show some leakage which mean the pointer will move up a little bit and stay there. This is a good schottky diode characteristic when checking on the diode. However if you measure a normal diode and you discovered that it has two readings then the diode is considered bad and need to be replace. A shorted schottky barrier diode will show two full scale readings registered at the panel meter which mean two ways of checking the pointer will point to zero ohms. If a technician or engineers do not know how to check a schottky diode, he or she may think that the diode have some leakage and need to replace. The worst part is diode schottky is hard to find in the market. Searching for schottky diodes replacement will take you time and it is not necessary if you know how to check it. The technician might just simply replace a 'normal diode' and hope that it will work. Well, the equipment will still not work because you have replaced a working diode (schottky diode) with another good normal diode! The actual cause is still out there and not the schottky diode!

Sometimes replacing a schottky diode with a normal diode may cause the equipment to be unstable or giving intermittent problem especially in the sensitive circuit section. The best is to replace with original part number or a specification that is higher than the original diode. Typical example of a part number for a schottky diode is 1N5819. Try check out this part number from google search engine and semiconductor replacement guide book and look at the data compare to normal general purpose diode, the more you are expose to this kind of technical stuff the more experience you will gain and in future if there is a schottky diode ever come across your repair bench you will definetly know what to do.