franky2006tw
Newbie level 1
How to make a high voltage schottky which is completely matching the applications of customer ?
Continue to Site
The Schottky diode (named after German physicist Walter H. Schottky) is a semiconductor diode with a low forward voltage drop and a very fast switching action. A typical application is discharge-protection for solar cells connected to lead-acid batteries. While standard silicon diodes have a forward voltage drop of about 0.6 volts, Schottky diodes voltage drop at forward biases of around 1 mA is in the range 0.15V to 0.45 V, which makes them useful in voltage clamping applications and prevention of transistor saturation. This is due to the higher current density in the Schottky diode.
A Schottky diode uses a metal-semiconductor junction as a Schottky barrier (instead of a semiconductor-semiconductor junction as in conventional diodes). This Schottky barrier results in both very fast switching times and low forward voltage drop.
It is often said that the Schottky diode is a "majority carrier" semiconductor device. This means that if the semiconductor body is doped N-type, only the N-type carriers (mobile electrons) play a significant role in normal operation of the device. No slow, random recombination of N- and P- type carriers is involved, so this diode can cease conduction faster than an ordinary PN rectifier diode. This property in turn allows a smaller device area, which also makes for a faster transition. Therefore broad-area Schottky diodes are useful in switch-mode power converters which operate at frequencies approaching 1 MHz. Small-area Schottky diodes are the heart of RF detectors and mixers, which often operate up to 5 GHz.
The most evident limitation of the Schottky diode is difficulty reaching high reverse-bias voltage ratings, and relatively high series resistance when high voltage ratings are attempted. Relatively high reverse leakage current may present an issue in some applications.
Commonly encountered Schottky diodes include the 1N5817 series 1 A rectifiers. Schottky metal-semiconductor junctions are featured in the successors to the 7400 TTL family of logic devices, the 74S, 74LS and 74ALS series, where they are employed as clamps in parallel with the collector-base junctions of the bipolar transistors to prevent their saturation, thereby greatly reducing their turn-off delays. (ALS stands for Advanced Low-power Schottky.)