While the Schottky diode has been on the market for decades, new developments and products have continued to enhance its features and extends the application possibilities. In addition to solar panels and cars, they are now also used in notebook computers, smart phones and tablet battery charger. However, what kind of diode which is suitable for use in selecting the right solution time and what should it be considered?
Because of its high switching speed, Schottky diodes mainly for high frequency applications up to the microwave range. This is also due to their low saturation capacity. Thus, they are generally used as the protection diode to reduce the induced voltage in the form of a freewheeling diode or rectifier diode in the switching power supply, it is also used as the demodulator of the detection circuit.
A different version
However, not all of Schottky diodes are the same. For example, most of the silicon for high voltage of 250V, and gallium arsenide, silicon carbide or silicon germanium semiconductor material is used as a blocking voltage of 200 to 1700V. Silicon Schottky diodes having a low threshold voltage of about 0.4V, 0.1V and even lower than the lower operating current. This is far below the voltage of about 1V semiconductor - semiconductor junction.
Schottky diode can be the collector base junction silicon bipolar transistor switched in parallel, in order to prevent saturation of the transistor, and the transistor can be significantly faster switching to the blocking state. However, they have a ratio of silicon-based semiconductor - semiconductor diode higher leakage current, and quickly leads to a high conduction losses at higher blocking voltage.
To reduce these shortcomings, Littelfuse has recently launched two new product lines: MBR DST and power semiconductors. MBR series rectifier diodes on a silicon-based Schottky diode technology, not only a low leakage current, and provides high temperature resistance and low forward voltage. They are very suitable for high frequency switching power supply, a freewheeling diode, DC / DC converter, and uninterruptible power polarity protection. They can also meet the general requirements for all commercial and industrial applications.
These diodes for harsh high temperature environment of a high-temperature condition having a junction guard ring, can increase strength and durability. Developers often use MBR Schottky rectifier diodes, since they have fast switching characteristics, low leakage current and low forward voltage, and having a higher impedance to a high junction temperature. Since they produce less heat than conventional diode, thus further reducing thermal and electrical losses.
Compared with the MBR series, the DST series of Schottky barrier rectifier having low forward voltage and lower leakage current, and thus it has a higher system efficiency. At the same time, they have a high saturation capacity, and therefore not suitable for ultra-high frequency applications. Otherwise, the two series have almost the same characteristics, also suitable for the same applications. The circuit design for a particular application, they have a variety of package types and a single chip or two-chip configuration is optional.
Littelfuse diode can also be customized for specific applications. The company also personalized response to customer needs in terms of functionality, packaging and delivery of consistent, it is possible to develop the perfect solution for a particular application.
Second, the practical application
Typical applications include Schottky diodes, such as solar panels or switch mode power supplies. The reason is that the current switched mode power supply is higher than the normal operating frequency of 20kHz, sometimes even up to smaller applications 200kHz. Thus, while DST has been popular, but the main use is in the field of diode MBR.
Today, the switching power supply is increasingly being used to convert alternating current to direct current, including laptops and tablet PCs power adapter, USB charger smart phones, desktop computers, network equipment, set-top boxes, wireless routers, and many other devices built-in power supply.
If a piece of equipment needed for its operation with a processor or memory unit and powered by alternating current (e.g., by an alternator home outlet or a car), the power switch is usually installed.
Power Rectifier thus mainly used for power applications, these applications alternating current from the alternator must be converted back to the various devices 5V, 9V, 16V or 24V DC. In automobiles, the DC to DC power supply of 12V or 24V battery current is converted into direct current motor vehicles various devices used 5V, 9V, 16V or other voltage.
Although reliable switching current and voltage is normally a DC to AC or DC to DC power supply main objectives and other electrical equipment, the goal is to prevent the backflow of the solar module. The solar cell made of a semiconductor material due to energy (e.g., electromagnetic radiation from the sun) to provide a charge carrier generating free.
In order to generate the charge carriers from the current, the positive and negative charge carriers to be oriented in different directions. This is typically accomplished by using an internal electric field, and the internal electric field of the semiconductor can be - to produce semiconductor junction - a semiconductor or metal. The latter can better prevent possible backflow because of their low forward voltage drop, thereby preventing power loss rectifier.
MBR Schottky diodes in the past dominated the market in all applications, because they are easier to produce and less expensive. Far Eastern manufacturers in particular, can provide these devices at very low prices. However, quality, durability, resistance to harsh environments and personalized adjustment is playing an increasingly important role; therefore, choose higher-priced products are often more rewarding in the long run.
In addition, the use of DST diodes are becoming more frequent, because in spite of its complex production process, but compared to MBR version is also not much more expensive, and because of their higher system efficiency to ensure a faster return on investment. By using improved technology has gradually solve the problem of high frequency applications; Seen in this light, DST is to conquer more and more applications.