Step recovery diodes produce an abrupt turn-off (step) time by allowing a very fast release of stored charge when switching from forward to reverse bias, and from reverse to forward bias. Single step recovery diodes consist of one diode built into the chip. Step recovery diode arrays are composed of multiple, discrete, usually unconnected diodes on a single silicon chip. Performance specifications for step recovery diodes include forward voltage, maximum allowable reverse voltage, reverse current, breakdown voltage, reverse recovery time, power dissipation, terminal capacitance, and operating temperature. Pin count and the number of embedded diodes are factors to consider when selecting an integrated circuit (IC) package. Step-recovery diodes that are sold in Europe must comply with the Restriction of Hazardous Substances (RoHS) directive from the European Union (EU).
Selecting Step Recovery Diodes
Diode application is an important parameter when selecting step recovery diodes. Rectifier diodes are electronic devices that allows current to flow in only one direction. Limiter diodes can be used as voltage limiters or in voltage limiter circuits. Switching diodes are designed for high-speed switching applications. Modulation diodes can be used in either AM or FM modulators. Amplification diodes are designed for amplifier circuits. By contrast, voltage regulation diodes are designed for voltage regulation circuits. Damper diodes are used in television sets and low leakage diodes are used in low leakage applications. Mixer diodes are also commonly available. Protector diodes are used to protect electronic components from unwanted transients such as current and voltage surges, electrostatic discharge (ESD), lightning, spikes and other signals that can imperil the operation or damage the component. Other types of step-recovery diodes are also available.
IC Package Types
Step recovery diodes use many different IC package types. Choices include: diode outline (DO), small outline diode (SOD), transistor outline (TO), small outline transistor (SOT) discrete package (DPAK), and metal electrode leadless face (MELF). Many different types of DO, SOD, TO, and SOT packages are available. MELF packages for step-recovery diodes include: QuadroMELF, MicroMELF, and MiniMELF. D2PAK is a large surface-mounted package that includes a heat sink. SC-59, SC-74, and SC-76 are plastic, surface-mounted packages with three leads. Powermite®3 is a compact, high power density surface mount rectifier package that offers low thermal resistance. Powermite®3 is a registered trademark of Diodes, Inc.
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Current Limiting Diodes
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General Purpose Diodes
General-purpose diodes are electric components that conduct electric current in only one direction, functioning similarly to a one-way valve.
Gunn and IMPATT Diodes
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High Voltage Diodes
High voltage diodes are designed for use in high-voltage applications.
Rectifier diodes are designed for use in rectification circuits. Rectifiers are used to convert AC to DC.
Schottky diodes in their simplest form consist of a metal layer that contacts a semiconductor element. The metal / semiconductor junctions exhibit rectifying behavior (i.e., the current passes through the structure more readily with one polarity than the other).
Zener diodes are PN junction devices that are designed to operate in the reverse-breakdown region.