Como Funciona o MOSFET: O Que Ninguém Te Explica nas Aulas Básicas

Understanding MOSFETs: How They Work

Introduction to MOSFETs

• The video aims to clarify the functioning of MOSFETs, addressing common misconceptions about testing them with a multimeter.

• MOSFETs are integral components in various electronic devices, including switch-mode power supplies and power electronics.

Structure and Functionality of MOSFETs

• A typical MOSFET has three terminals: gate, drain, and source. The video uses the IRFZ48N model for illustration.

• It is crucial to consult the datasheet for accurate pin configuration as it may vary across different models.

Types of MOSFETs

• There are two main types of MOSFETs: N-channel and P-channel; N-channel types are more commonly found in the market.

• An N-channel MOSFET requires a positive pulse at the gate to allow current flow between drain and source.

Operation Mechanism

• The operation resembles that of a switch, where a positive pulse enables conduction while a negative pulse blocks it.

• Unlike bipolar transistors that rely on current at their base, MOSFET gates operate on voltage with very low current requirements.

Key Characteristics

• The high impedance nature of the gate allows for minimal current draw (in microamperes), making it efficient for rapid switching applications.

• This efficiency enables MOSFET usage in high-frequency circuits like switch-mode power supplies.

Testing Your MOSFET

Testing Methods Overview

• The presenter will demonstrate two methods for testing a MOSFET without removing it from its circuit board.

First Testing Method: On-Circuit Measurement

• Using an automation control board as an example, measurements will be taken using a multimeter set to diode mode.

• A successful test shows approximately 0.5V when measuring between drain and source; reversing leads should indicate no conduction.

Second Testing Method: Off-Circuit Measurement

• For further verification, testing can also be done with the component removed from the circuit.

How to Test a MOSFET Using a Multimeter

Understanding MOSFET Functionality

• The speaker demonstrates how to connect a multimeter to test a MOSFET by placing the negative lead on the CCE and the positive lead on the gate. Initially, there is no conduction observed.

• By applying a positive pulse to the gate and checking back at the drain, conduction is noted at 0.765 on the multimeter. This process can be repeated multiple times, indicating consistent behavior of the component.

• A negative pulse applied to the gate results in cutting off conduction, confirming that control over the MOSFET's state is effective through gate voltage manipulation.

Practical Application and Learning Resources

• The explanation provided clarifies not only how to test but also deepens understanding of how MOSFET components function, aiding in diagnostics for electronic boards.

• Viewers are encouraged to engage with content by liking and subscribing for weekly updates. Additionally, free resources such as an electronics basics booklet are available through direct contact via Instagram for those interested in further learning about component functionality and maintenance techniques.