MOSFET power dissipation is the sum of the conduction loss and the switching losses. These power losses are very different from each other. Conduction loss is the static loss wherein the main contributor is the drain to source on-state resistance of the MOSFET as well as the drain current. While switching losses are dynamic losses that are dependent on the
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MOSFET could be used as a switch or amplifier. Regardless of the application, there is a conduction loss. Let’s explore what is the meaning of conduction loss and how to compute MOSFET conduction loss. Conduction loss is the main contributor to MOSFET power dissipation when operating in a non-switching application. Even in switching applications, conduction loss is still very significant
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How to get MOSFET correct RDSon value is the pre-requisite to compute the MOSFET conduction loss or static power dissipation. RDSon is the drain to source on-state resistance of the MOSFET. The term “correct” is relative to the target result. Supposing the target is to compute the maximum power dissipation, then the correct RDSon value must be the worst-case value.
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There are two types of losses in MOSFET. One is conduction loss and the other one is switching loss. Conduction loss is explained in detail here. Switching loss is not as easy as computing the conduction loss. There are many parameters to consider. You need to understand these parameters to select the correct values. However, you don’t need any more
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The important MOSFET design parameter to consider during circuit design are gate threshold voltage, on-state resistance, current stress, voltage stress, power stress and thermal stress. Threshold voltage refers to the gate to source voltage requirement for the MOSFET to turn on. On-state resistance is the equivalent resistance between drain to source when the MOSFET is on. Current stress is related
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You may not know how to use MOSFET as reverse battery protection. The most common method is using a diode. However, diode voltage drop is high and this will creat issue in low voltage circuits. That is the reason many use MOSFET as reverse battery protection due to its very low on state voltage drop.
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MOSFET RDSon temperature coefficient is positive. Meaning, it will increase with increasing temperature. In this article I will discuss and interpret MOSFET RDSon temperature coefficient that is often given in the form of graph in datasheets like below. Datasheets may also provide actual RDSon data with respect to junction temperature instead of the coefficient like below. Datasheets also provides tabular
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Below are the guides on how to know if MOSFET is defective. These are the most common techniques that can be used to check if MOSFET is defective. Step #1 on How to Know if MOSFET is Defective :Diode Check The first thing we will try on how to know if MOSFET is defective is to check the diode drop.
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High side driver design using PMOS is an easy approach on driving a high side load. High side driver is the term used because once the switch turns on, it will connect the load to the circuit supply to complete the current path. A load is not limited to resistors, it can also an inductive such as relay and lamp.
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There are only few steps to consider in dealing with low side switch design using NMOS with a resistive load. Low side switch is the term used because once the switch turns on; it will connect the load to the circuit ground to complete the current path. A load is not limited to resistors, it can also an inductive such
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