What are the main parameters of Schottky diodes

What are the main parameters of Schottky diodes

Schottky diods are widely used in power management, rectification, protection circuits, and other scenarios due to their low forward voltage, fast recovery time, and low power consumption. Understanding the main parameters of Schottky diods is crucial for ensuring circuit performance when selecting them.

1. Forward voltage

The forward voltage is a key parameter of Schottky diods. Compared to the forward voltage of standard silicon diodes, which is around 0.7V, the forward voltage of Schottky diods is typically between 0.2V and 0.45V. This low forward voltage means that in the conducting state, the voltage drop across the diode is smaller, thereby reducing power loss. In high-performance power management applications such as switch mode power supplies (SMPS) and DC-DC converters, low forward voltage drop can significantly improve efficiency. Therefore, when engineers choose Schottky diods, they need to select appropriate parameters based on the operating current in the application to minimize power consumption.

2. Reverse leakage current

The leakage current of Schottky diods during reverse bias is usually higher than that of ordinary PN junction diodes. This is because Schottky diods adopt a structure of metal semiconductor contact, which results in higher reverse current when reverse biased. This parameter is very important for circuits that require high reliability, such as low-noise circuits. If the reverse leakage current is too high, it may cause additional power loss and may affect the stability of the circuit. The reverse leakage current of Schottky diodes of different models varies greatly, so when selecting, it is necessary to weigh the leakage current and other performance parameters according to the application requirements.

3. Reverse breakdown voltage

Reverse breakdown voltage refers to the phenomenon where a diode begins to experience significant reverse current when the applied reverse voltage exceeds this value, leading to breakdown. In practical applications, the reverse breakdown voltage of the selected Schottky diod should be at least a certain margin higher than the maximum reverse voltage that may occur in the circuit. For example, in a rectifier circuit, after the input AC voltage is rectified, its reverse voltage may reach a very high value, so it is necessary to choose Schottky diods with high breakdown voltage. Typically, the reverse breakdown voltage of Schottky diods ranges from 20V to 200V, depending on the actual operating voltage of the circuit.

4. Maximum average rectified current

The maximum average rectified current is the maximum average current that a Schottky diod can pass through during operation. This parameter indicates the current size that the diode can handle in continuous operation. In the design, it is necessary to ensure that the maximum rectified current of the selected Schottky diod is greater than the actual operating current of the circuit to avoid damage to the diode due to overcurrent. In addition, the working temperature also has an impact on the current handling capability, so the design needs to consider the effect of temperature rise on the performance of the diode.
5. Junction capacitance

Junction capacitance is the parasitic capacitance at the PN junction or metal semiconductor interface of a diode, typically measured in picofarads (pF). In high-frequency applications, junction capacitance may have a significant impact on circuit performance, especially in radio frequency (RF) circuits or high-speed signal processing. The junction capacitance of Schottky diods is usually smaller, making their performance better than traditional diodes in high-frequency circuits. Therefore, for high-speed switch circuits or high-frequency application scenarios, it is crucial to choose Schottky diods with low junction capacitance.

6. Switching time

Schottky diods have a very fast switching speed due to their structural characteristics. Compared to traditional diodes, Schottky diods have very short switching times, typically only a few nanoseconds or even lower. The speed of switching time directly affects the switching frequency of the circuit, especially in switching power supplies or high-speed signal processing, where the speed of switching time can affect conversion efficiency and signal integrity. Therefore, when designing high-frequency switch circuits, choosing Schottky diodes with fast switching speeds can improve the overall performance of the circuit.

7. Thermal resistance

Thermal resistance refers to the thermal impedance of a diode from the junction to the environment or from the junction to the pin, measured in ℃/W. Schottky diods generate heat during operation, and the lower the thermal resistance, the easier it is for the device to dissipate heat, thereby avoiding performance degradation or damage caused by overheating. In high-power applications, thermal management is particularly important, so choosing a low thermal resistance Schottky diod, combined with appropriate heat dissipation design, can effectively improve the reliability and lifespan of the device.

8. Packaging form

The packaging form affects the heat dissipation performance and installation method of Schottky diods. The common types of packaging include SMD (Surface Mount) and THT (Through Hole Installation). When choosing packaging, it is necessary to weigh the power requirements, heat dissipation requirements, and PCB design of the circuit. For high-power applications, packages with good heat dissipation performance, such as TO-220, are usually chosen; For low-power or space limited applications, SMD packaging such as SOD-123 can be chosen.

Schottky diods play an important role in various applications due to their advantages such as low forward voltage, fast switching speed, and low junction capacitance. When choosing Schottky diods, it is important to understand and comprehensively consider parameters such as forward voltage, reverse leakage current, reverse breakdown voltage, maximum rectification current, junction capacitance, switching time, thermal resistance, and packaging form to ensure the performance and reliability of the circuit in practical applications.