What impact do parameters such as the voltage withstand value, on-resistance, and maximum current of a MOSFET have on circuit design?

Did you know? The charging speed of mobile phones, the range of electric vehicles, and even the noise of home air conditioners are all related to MOSFETs. MOSFET field-effect transistors are often referred to as "electronic switches" by engineers. Today, Heketai will analyze how the three most important parameters of MOSFETs - voltage withstand value, on-resistance, and maximum current - actually affect our circuit design.

1. Voltage Withstand Value: The Voltage Resistance Capability of MOSFETs

The voltage withstand value VDS is a threshold; once exceeded, the MOSFET will "stop working". For example, in a 12V circuit for charging a mobile phone, a MOSFET with a 20V withstand value may seem sufficient, but the voltage of a car power supply can surge to 15V, in which case the 20V MOSFET may "burn out". Therefore, the professional recommendation is to select a MOSFET with a withstand value of "operating voltage × 1.5 times". A 12V circuit equipped with a 30V withstand value MOSFET is reliable. For high-voltage scenarios such as photovoltaic inverters, MOSFETs with a withstand value of 600V or higher are required.

2. On-Resistance: The Thickness of the Water Pipe for Current Flow

The smaller the on-resistance RDS(ON), the smaller the "resistance" when current flows through. For example, with a 10A current, a MOSFET with a 50mΩ resistance will generate 5W of heat, which is equivalent to the heat generated during fast charging of a mobile phone; while a 20mΩ MOSFET only generates 2W of heat. This is why electric vehicle battery management systems choose low-resistance MOSFETs. For example, each 1mΩ reduction in resistance may increase the range by 1km. The on-resistance of HKTE180N10 is only 2.3mΩ, which can significantly reduce heat generation, thereby improving energy efficiency and range. In actual circuit design, it is necessary to calculate in combination with system efficiency.

3. Maximum Current: The Size of the MOSFET

The maximum current ID is the current that a MOSFET can pass through at one time; exceeding it will cause it to "be overwhelmed". The "4A current" marked on the specification sheet is usually the current under normal temperature, but it may only be able to pass "3A" at high temperatures in summer. During design, never let the current through the MOSFET exceed the limit; leaving a 20% margin is the safest. For example, if a 3A current is needed, a 4A MOSFET should be selected. The TO-252 packaged HKTD80N03 is nominally 80A, but it needs to be adjusted according to the junction temperature below 150°C and heat dissipation conditions. The maximum current parameter is related to the heat dissipation capacity of the package.

A Selection Rhyme That Even 普通人 Can Understand

Can't remember complex parameters? Just remember these three points:

• Withstand value depends on the scenario: choose 20-30V for low-voltage (mobile phones, headphones), and 600V or higher for high-voltage (electric vehicles, air conditioners);
• Choose a small resistance: under the same conditions, the smaller the on-resistance, the more energy-efficient;
• Leave a margin for current: select a MOSFET with a current 1.2 times the actual required current to avoid "overheating" in summer.

In fact, you don't need to understand too many professional terms to choose a MOSFET; just grasp the three characteristics of "withstanding voltage, smooth conduction, and no overload". As a brand specializing in semiconductor MOSFETs, Heketai has long optimized the parameters of MOS transistors, so engineers can directly select the models. Next time you take apart a charger, you might as well think about and look at the MOS transistors inside!

Company Introduction

Founded in 1992, Heketai is a professional high-tech and specialized enterprise integrating R&D, design, production, and sales of components. It focuses on providing cost-effective component supply and customization services to meet the R&D needs of enterprises.

Product supply categories: covering semiconductor packaging materials, passive components such as resistors/capacitors/inductors; as well as MOSFETs, TVS, Schottky diodes, voltage regulators, fast recovery diodes, bridge rectifiers, diodes, triodes, power devices, power management ICs, etc., providing one-stop procurement for R&D and production.

Two intelligent manufacturing centers: South China and Southwest manufacturing centers (Huizhou 75,000㎡ + Nanchong 35,000㎡) are equipped with more than 3,000 advanced equipment and testing instruments; in 2024, 3 new semiconductor material subsidiaries were added to control production capacity and delivery efficiency from the source.

Providing packaging and testing OEM foundry services: supporting sample customization and small-batch trial production, combined with more than 100 patented technologies and ISO9001, IATF16949 certification systems, to ensure that "quality first" runs through every link from R&D to delivery.

Heketai always takes "customer first, innovation-driven" as its core, providing stable and reliable components for enterprises.

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