relations between MOSFET power loss and diode loss?

relations between MOSFET power loss and diode loss?

relations between MOSFET power loss and diode loss? Switched-mode power supply (SMPS for short), also known as switching power supply and switching converter, is a high-frequency power conversion device and a kind of power supply.

Switching losses include conduction losses and cutoff losses. Conduction loss refers to the power loss generated by a power transistor from cut-off to conduction. Cutoff loss refers to the power loss generated by a power transistor from conduction to cutoff. Switching loss includes turn on loss and turn off loss, which are often discussed in hard switching and soft switching. The so-called turn on loss means that when a non ideal switch is turned on, the voltage of the switch does not immediately drop to zero, but has a Fall time. At the same time, its current does not immediately rise to the load current, but also has a rise time. During this period, there is an overlap zone between the current and voltage of the switch tube, which will result in losses, which are called turn-on losses.

By analogy, the reason for the shutdown loss can be determined, and it will not be repeated here. Another meaning of switching loss refers to the need to charge and discharge parasitic capacitors when switching large MOS transistor in a switching power supply, which can also cause losses.

In the process of device design and selection, it is necessary to calculate the working process losses of MOSFET in advance (the so-called advance calculation refers to the approximate calculation in theory using the parameters provided in the device specification, the calculated values and expected waveforms of the working circuit, and the formula applied in the absence of the ability to test each working waveform).

Generally speaking, power MOSFET and diode are basic components in electronic product design and electrical circuit system, and their electronic components have their own limit parameters of conductive resistance and working environment. How do electronic engineers grasp the power consumption, service life performance and quality of electronic components, as well as power MOS tubes and diodes loss?

Electronic product designers and engineering assistants need to consider two different situations, namely the worst-case scenario in which electronic products work and the real situation in which devices work. Starting from the procurement brand and selection of electronic components, select the correct components for circuit products, and then find similar and consistent technical parameter values in the electronic component specifications based on actual applications, such as the selection of MOS channel types, current and voltage values.

The loss of diode switches is actually a very important indicator. The self heating damage on the working circuit of electronic components, as well as the heating caused by losses caused by external DC power, can to some extent cause instantaneous and local heating, leading to damage. For example, the thermal resistance between the semiconductor junction of the packaged device and the environment, and the conduction loss of the power MOSFET transistor when the built-in diode is damaged, can be calculated