onsemi MUR120G Ultrafast Rectifier: Datasheet, Pinout, and Application Circuits

The MUR120G from onsemi is a highly efficient ultrafast recovery rectifier designed for high-frequency power conversion applications. Its exceptional switching speed and low forward voltage drop make it a preferred choice for engineers designing switch-mode power supplies (SMPS), freewheeling diodes, and reverse battery protection circuits. This article provides a detailed overview of its datasheet specifications, pinout configuration, and common application circuits.

Datasheet Overview and Key Specifications

The MUR120G is part of a series of rectifiers renowned for their ultrafast recovery time, which is crucial for minimizing switching losses and improving overall efficiency in high-frequency circuits. Key absolute maximum ratings from the datasheet include a repetitive peak reverse voltage (VRRM) of 200V and an average forward rectified current (IF(AV)) of 1A. Its most critical dynamic characteristic is its trr (reverse recovery time) of 35ns, which ensures minimal charge storage and a swift transition from the on-state to the blocking state. This diode also features a low forward voltage drop (VF typically 0.92V at 1.0A), which contributes to reduced power dissipation and higher efficiency.

Pinout and Package

The MUR120G is offered in the popular DO-41 axial leaded package. This package is designed for through-hole mounting (THT) on printed circuit boards (PCBs). The pinout is standard for a diode: the cathode is marked with a distinctive band on one end of the component's body, while the opposite end is the anode. Correct orientation is vital for the circuit to function as intended.

Common Application Circuits

1. Switch-Mode Power Supply (SMPS) Output Rectifier: In SMPS designs, particularly flyback and forward converters, the MUR120G is often used as the output rectifier. Its fast recovery characteristic prevents excessive ringings and voltage spikes that occur during the switching cycle, protecting sensitive components and ensuring clean DC output.

2. Freewheeling or Flyback Diode: In inductive load circuits, such as those driving motors or relays, the MUR120G acts as a freewheeling diode. It provides a safe path for the current to circulate when the driving switch (like a MOSFET or transistor) is turned off, preventing damaging voltage spikes that could destroy the switching element.

3. Reverse Voltage Protection: A simple yet effective circuit for protecting sensitive electronics from accidental reverse polarity connection can be built using the MUR120G. Placed in series with the positive power input line, the diode will only conduct when the polarity is correct, blocking current flow if the voltage is reversed.

ICGOODFIND Summary

The onsemi MUR120G stands out as a robust and highly efficient solution for high-speed rectification needs. Its excellent combination of a 200V voltage rating, ultrafast 35ns recovery time, and low forward voltage makes it exceptionally suitable for demanding applications in power supply design and inductive load management. For engineers seeking reliability and performance in switching power circuits, the MUR120G remains a top contender.

Keywords:

Ultrafast Rectifier, Reverse Recovery Time, Switch-Mode Power Supply (SMPS), Freewheeling Diode, DO-41 Package