Analysis of Heating Causes of Power MOSFETs in Power Management Scenarios

During operation, power MOSFETs inevitably generate heat, leading to a rise in temperature. When the temperature of MOSFETs is too high, it will not only reduce system efficiency but also may cause degradation of device performance, shorten service life, and even trigger system failures. Hekotai takes you to deeply understand the causes of heating of power MOSFETs in power management scenarios, helping engineers optimize power supply design and improve system stability.

Heating Principle

In power management applications, power MOSFETs mainly work in the on-state and off-state. In switching power supplies, they switch rapidly between the two states to achieve the conversion and control of electrical energy. The essential cause of heating is the energy loss generated during the conversion of electrical energy, which mainly includes four types: conduction loss, switching loss, driving loss, and leakage current loss. These losses will eventually be converted into heat, causing the temperature of the MOSFET to rise.

• Conduction loss: When the MOSFET is in the on-state, there is a certain resistance in the channel, called on-resistance. When current flows through it, Joule heat is generated, resulting in heating.
• Switching loss: During the switching process of the MOSFET, energy loss occurs in the overlap region of voltage and current. This part of the loss is called switching loss, which is more obvious especially in hard-switching topologies.
• Driving loss: The energy consumed by the driving circuit to charge and discharge the gate capacitance of the MOSFET. This part of the loss is proportional to the gate charge and switching frequency.
• Leakage current loss: Even when the MOSFET is in the off-state, there is still a small leakage current, and this part of the current will also produce a certain power loss.

Causes of Heating

The heating of power MOSFETs in power management scenarios is the result of the combined effect of multiple factors. These factors can be divided into the following categories:

• Current-related factors: Excessive on-state current, load current fluctuations, thermal runaway effects caused by current, etc.
• Voltage-related factors: Excessively high drain-source voltage, voltage stress, reverse recovery loss of the body diode, etc.
• Frequency-related factors: Excessively high switching frequency, indirect impact of frequency on conduction loss, etc.
• Heat dissipation-related factors: Improper heat dissipation design, excessive thermal resistance, excessively high ambient temperature, etc.
• Driving-related factors: Inappropriate gate driving voltage, insufficient driving current, gate oscillation, etc.
• Other factors: Improper device selection, unreasonable PCB layout, influence of operating environment temperature, etc.

Suggestions for Heating Optimization

Based on the above analysis, we can put forward the following optimized design suggestions to reduce the heating of power MOSFETs in power management scenarios:

• Reasonably select device parameters:

Choose the appropriate MOSFET model according to application requirements, and balance parameters such as on-resistance, gate charge, and switching speed.

For high-temperature and high-frequency applications, consider using new devices such as SiC MOSFETs or GaN HEMTs.

• Optimizing Circuit Design:

Select an appropriate topology; for example, a soft-switching topology can significantly reduce switching losses.

Design the gate drive circuit reasonably to ensure sufficient drive voltage and current, and optimize the gate resistance.

Adopt buffer circuits or clamping circuits to suppress voltage spikes and oscillations.

• Optimizing Heat Dissipation Design:

Choose a suitable heat sink to ensure adequate heat dissipation capacity.

Use thermal grease or thermal pads to optimize the thermal contact between the device and the heat sink.

Optimize the PCB layout, increase the heat dissipation area, and ensure a good heat dissipation path.

• System-Level Optimization:

Select the switching frequency reasonably to find a balance between conduction loss and switching loss.

Consider derating, especially in high-temperature environments.

Design appropriate protection circuits to prevent overheating caused by abnormal conditions such as overcurrent and overvoltage.

Summary

The heating of power MOSFETs in power management scenarios is a complex issue involving the interaction of multiple factors. By deeply understanding these factors and their influence mechanisms, engineers can take effective measures during the design phase to reduce the heating of MOSFETs and improve the efficiency and reliability of the system. In practical applications of Hekotai MOSFETs, it is necessary to comprehensively consider various factors according to specific application requirements and conditions and conduct system-level optimization design.

Company Introduction

Founded in 1992, Hekotai is a professional high-tech and specialized enterprise integrating R&D, design, production, and sales of components.

Products include:

1. Semiconductor packaging materials; 2. Passive components, mainly including resistors, capacitors, inductors; 3. Semiconductor discrete devices, mainly including MOSFETs, TVS, Schottky diodes, voltage regulators, fast recovery diodes, bridge rectifiers, diodes, triodes, power devices, power management ICs, and other integrated circuits.

Hekotai has two intelligent manufacturing centers:

1. The manufacturing center in South China is located in Hekotai Technology Intelligent Manufacturing Park, Boluo County, Huizhou City, with a construction area of 75,000 square meters. It has more than 1,000 sets of advanced equipment and testing instruments, and is equipped with a group logistics distribution center locally. The Dongguan Tangxia production center is the current production base.
2. The manufacturing center in Southwest China is located in Kechuang Center, Shunqing District, Nanchong City, Sichuan Province, with a plant area of 35,000 square meters and about 2,000 sets of advanced equipment and testing instruments.

In 2024, Hekotai comprehensively expanded its product line and established three subsidiaries in Nanchong, Sichuan, namely Shunxin Semiconductor, Nanchong Anhao, and Nanchong Jingke, which are mainly responsible for the R&D and production of semiconductor packaging materials. After the expansion of the product line, it will meet customer needs to the greatest extent.

Hekotai adheres to the business philosophy of customer first, quality first, innovation-driven, and people-oriented, providing customers with one-stop application solution services. At the same time, Hekotai provides comprehensive services such as OEM foundry for semiconductor chip and discrete device packaging and testing.

Hekotai has accumulated rich core technical reserves in integrated circuit design, chip testing, discrete device process design, reliability testing, etc., and has more than 100 national invention patents, utility model patents, etc.

Hekotai has passed ISO9001, ISO14001, and IATF16949 system certifications.

Products are widely used in power supplies, lighting, medical electronics, small household appliances, communications, security instruments, industrial control, automotive electronics, and other fields.

Scan to contact Hekotai

Sales phone: 18823438533 (WeChat same number)

Landline: 0755-82565333

Email: hkt@heketai.com