Schottky diodes (named after inventor Walter Schottky) are typically found in power supplies and in devices that use radio frequencies, but new generation diodes have increased their use in a wide range of technologies. Because of the variety of applications in which they can be used, Schottky diodes come in sizes ranging from miniature to large. But regardless of their size, there are common rules for using Schottky diodes in electrical circuits.
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Identify the location for the Schottky diode on the schematic. The diode symbol is an arrow with its point at a vertical line; however, the vertical line denoting a Schottky diode has hooks top and bottom that go in opposite directions. On the printed circuit board, the diode component designator is the letter D.
Identify the direction of current flow on the diode. Most diodes use a P- and N-type semiconductor design, which means special type-P receptive material is placed near type-N conductive material to induce current flow in one direction. The Schottky diode is different because it uses a pure metal to silicon semiconductor junction. The metal-to-semiconductor relationship can also be described as anode to cathode, and all Schottky diodes have a line that indicates its cathode end; its other end being the anode, which receives the incoming current flow and directs it to the cathode.
Insert the Schottky diode in the circuit making sure the line (cathode) end is placed correctly. The most common Schottky diode has a wire extending from each side to allow inserting in and soldering to a printed circuit board. Drop-in versions have prongs that plug into a circuit board. Larger diodes, such as those used in micro-converters for power supplies and solar cells, are bolted to terminals with screws.
Test the voltage on both sides of the diode using a DMM or digital multimeter. The Schottky diode should show a voltage drop on the cathode side and an open reading on the anode side. As electricity flows across the diode, there is a dip in the current called a forward voltage drop. For Schottky diodes, this drop ranges from 0.15 to 0.45 volts (compared to 0.7 to 1.7 volt drops for other diodes).
Adding Schottky Diodes to an Electrical Circuit
Tips and warnings
- Most electronic components including diodes are made of silicon, but SiC Schottky diodes are available now that are made of silicon carbide -- a compound of carbon and silicon that can withstand high temperatures for use in military and aerospace applications like satellites and missiles. There are also GaN Schottky diodes made of Gallium nitride for use in high power and frequency devices.
- Excessive current and heat are common causes of failure in all diodes including the Schottky.
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- "Microwave Product Digest;" Schottky Diodes; Rick Cory; February 2009;
- Team Novak; Schottky Diode;
- "Global Banking News (GBN)"; Infineon Introduces Third Generation Silicon Carbide Schottky Diodes; February 19, 2009
- "PR Newswire"; STMicroelectronics and Velox Semiconductor to Launch GaN Schottky Diodes for Power Applications; November 13, 2006
- "Electronic Design"; Drop-in Schottkys double current density, save space; December 9, 2002
- AeroElectric Connection; Installation Instructions AEC9001 Schottky Power Diode; December 7, 2008;