Schottky rectifier is a metal‑semiconductor junction diode with ultra‑low forward voltage drop and fast switching speed. It is widely used in secondary side rectification of switching power supplies, reverse‑current blocking circuits and low‑voltage high‑current power modules.
Working Principle
Different from PN‑junction diodes, Schottky diode forms barrier by contact between metal and semiconductor material. It features no minority‑carrier storage effect, so it can complete turn‑off action in extremely short time. Under forward bias, it maintains low forward voltage drop; reverse bias state bears specified reverse withstand voltage for blocking reverse current.
Main Classification
Package forms include through‑hole axial, TO‑220 power package and multiple SMD chip packages. According to withstand voltage grade, low‑voltage type below 100V occupies most power supply scenarios, and medium‑high‑voltage models serve special industrial equipment. Products are divided into general‑purpose rectification type and high‑efficiency low‑VF optimized type.
Key Electrical Parameters
Repetitive peak reverse voltage VRRM defines maximum safe reverse voltage. Average forward current IF represents continuous rectification capacity. Forward voltage VF determines conduction loss. Reverse leakage current IR is a critical index for thermal stability. Junction capacitance affects high‑frequency switching performance. Maximum junction temperature and power dissipation set thermal derating standard.
Circuit Design Guidelines
Reserve sufficient derating margin for reverse voltage under surge condition. Pay close attention to reverse leakage current rise caused by temperature increase. For high‑frequency rectification scenario, select low junction‑capacitance model. Parallel multiple devices for ultra‑large‑current application and ensure current balance. Avoid long‑term operation close to maximum junction temperature.
PCB Layout Suggestions
Shorten high‑current rectification loop trace to reduce conduction loss and spike noise. Place Schottky diode close to transformer or inductor terminal. Widen copper area for heat dissipation to control junction temperature. Keep high‑speed switching trace away from sensitive signal wiring. SMD device pads should strictly follow datasheet specifications.
Common Failure Modes
Thermal runaway caused by excessive reverse leakage at high temperature leads to short‑circuit breakdown. Over‑voltage surge destroys metal‑semiconductor junction. Excessive forward current causes burnout of chip. Poor heat dissipation accelerates device aging. High‑frequency oscillation occurs when layout loop inductance is too large.
Market Application Trend
High‑performance low‑VF SMD Schottky diodes are widely used in compact power adapters. High‑voltage Schottky products expand to new‑energy related fields. Composite rectifier chips integrate Schottky diode and peripheral protection to simplify power‑supply design.
