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Schottky Rectifiers have been used in the power supply industry for approximately 15 years. During this time, significant fiction as well as fact has been associated with this type of rectifier. The primary assets of Schottky devices are switching speeds approaching zero-time and very low forward voltage drop (VF). This combination makes Schottky barrier rectifiers ideal for the output stages of switching power supplies. On the negative side, Schottky devices are also known for limited high-temperature operation, high eakage and limited voltage range BVR. Though these limitations exist, they are quantifiable and controllable, allowing wide application of these devices in switch mode power supplies.

Zener diodes regulate voltage by acting as complementary loads, drawing more or less current as necessary to ensure a constant voltage drop across the load. This is analogous to regulating the speed of an automobile by braking rather than by varying the throttle position: not only is it wasteful, but the brakes must be built to handle all the engine's power when the driving conditions don't demand it. Despite this fundamental inefficiency of design, zener diode regulator circuits are widely employed due to their sheer simplicity. In high-power applications where the inefficiencies would be unacceptable, other voltage-regulating techniques are applied. But even then, small zener-based circuits are often used to provide a “reference” voltage to drive a more efficient amplifier circuit controlling the main power.

For most power application, half-wave rectification is insufficient for the task. The harmonic content of the rectifier’s output waveform is very large and consequently difficult to filter. Furthermore, the AC power source only supplies power to the load one half every full cycle, meaning that half of its capacity is unused. Half-wave rectification is, however, a very simple way to reduce power to a resistive load. Some two position lamp dimmer switches apply full AC power to the lamp filament for “full” brightness and then half-wave rectify it for a lesser light output.

One advantage of remembering this layout for a bridge rectifier circuit is that it expands easily into a polyphase version in Figure below

Despite the fact that Schottky barrier diodes have many applications in today's high tech electronics scene, it is actually one of the oldest semiconductor devices in existence. As a metal-semiconductor devices, its applications can be traced back to before 1900 where crystal detectors, cat's whisker detectors and the like were all effectively Schottky barrier diodes.

The Schottky diode symbol used in many circuit schematic diagrams may be that of an ordinary diode symbol. However it is often necessary to use a specific Schottky diode symbol to signify that a Schottky diode rather than another one must be used because it is essential to the operation of the circuit. Accordingly a specific Schottky diode symbol has been accepted for use. This Schottky diode symbol is shown below:

Schottky rectifiers have been used in the power supply industry for approximately 15 years. During this time, significant fiction as well as fact has been associated with this type of rectifier. The primary assets of Schottky devices are switching speeds approaching zero-time and very low forward voltage drop (VF). This combination makes Schottky barrier rectifiers ideal for the output stages of switching power supplies. On the negative side, Schottky devices are also known for limited high-temperature operation, high leakage and limited voltage range BVR. Though these limitations exist, they are quantifiable and controllable, allowing wide application of these devices in switch mode power supplies.

High leakage, when associated with standard P-N junction rectifiers, usually indicates “badness,” implying poor reliability. In a Schottky device, leakage at high temperature(75 °C and greater) is often on the order to several milliamps, depending on chip size. In the case of Schottky barrier rectifiers, high-temperature leakage and forward voltage drop are controlled by two primary factors: the size of the chip’s active area and the barrier height (φB).

Reverse Voltage - 20 to 40 Volts Forward Current - 3.0 Amperes

FEATURES

• Plastic package has Underwriters Laboratory Flammability Classification 94V-0
• Metal silicon junction, majority carrier conduction
• Guardring for over voltage protection
• Low power loss, high erriciency
• High current capability, low forward voltage drop
• High surge capability
• For use in low voltage, high frequency inverters, free wheeling, and polarity protection applications
• High temperature soldering guaranteed:
  250℃ /10 seconds, 0.375”(9.5mm) lead length,5 lbs. (2.3kg) tension

Diode have many types: ordinary rectifier diodes, ultra-fast rectifier diodes, transient voltage suppression diodes, switching diodes, high voltage diodes, diode bridge rectifier, SMT surface mount fast recovery diodes, surface-mount schottky diodes SMD, fast recovery rectifier diodes, schottky diodes, bi-directional trigger diodes, zener diodes,damping diodes, ordinary surface mount diodes SMT, SMT surface mount ultra-fast diodes, TO-220 packaged diodes, power snubber diode, etc.

Below are Kingtronics bridge rectifier full list, do you buy any of these? Kindly send your inquiry to info@kingtronics.com

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Kingtronics team

A Zener Diode is a special kind of diode which permits current to flow in the forward direction as normal, but will also allow it to flow in the reverse direction when the voltage is above a certain value - the breakdown voltage known as the Zener voltage.

The Zener voltage of a standard diode is high, but if a reverse current above that value is allowed to pass through it, the diode is permanently damaged. Zener diodes are designed so that their Zener voltage is much lower - for example just 2.4 Volts. When a reverse current above the Zener voltage passes through a Zener diode, there is a controlled breakdown which does not damage the diode. The voltage drop across the Zener diode is equal to the Zener voltage of that diode no matter how high the reverse bias voltage is above the Zener voltage.

The illustration above shows this phenomenon in a Current vs. Voltage graph. With a Zener diode connected in the forward direction, it behaves exactly the same as a standard diode - i.e. a small voltage drop of 0.3 to 0.7V with current flowing through pretty much unrestricted. In the reverse direction however there is a very small leakage current between 0V and the Zener voltage - i.e. just a tiny amount of current is able to flow. Then, when the voltage reaches the breakdown voltage (Vz), suddenly current can flow freely through it.

Uses of Zener Diodes

Since the voltage dropped across a Zener Diode is a known and fixed value, Zener diodes are typically used to regulate the voltage in electric circuits. Using a resistor to ensure that the current passing through the Zener diode is at least 5mA (0.005 Amps), the circuit designer knows that the voltage drop across the diode is exactly equal to the Zener voltage of the diode.

A Zener diode can be used to make a simple voltage regulation circuit as pictured above. The output voltage is fixed at the Zener voltage of the Zener diode used and so can be used to power devices requiring a fixed voltage.

If you have any inquiry about Zener diode, pls contact info@kingtronics.com

Diodes can switch analog signals. A reverse biased diode appears to be an open circuit. A forward biased diode is a low resistance conductor. The only problem is isolating the AC signal being switched from the DC control signal. The circuit in Figure below is a parallel resonant network: resonant tuning inductor paralleled by one (or more) of the switched resonator capacitors. This parallel LC resonant circuit could be a preselector filter for a radio receiver. It could be the frequency determining network of an oscillator (not shown). The digital control lines may be driven by a microprocessor interface.

Kingtronics www.kingtronics.com provide Fast Switching Diode LL4148 Minimelf SOD80 .The features of Fast Switching Diode LL4148 Minimelf SOD80 are below:

• LL4148 small signal diode
• Fast switching surface mount diode
• Low reverse leakage
• Fast switching speed
• Maximum power dissipation 500mW
• High stability and high reliability