Why pulsed drain current is higher than continuous drain current in MOSFETs

[hioyo]

Why is pulsed drain current higher than continuous drain current in MOSFETs?
In MOSFET data-sheets, pulsed drain current is much higher than (by 4x) continuous drain current.
What is the reason behind thi

 

[danadakk]

Understanding MOSFET Current Rating in Datasheets | Homemade Circuit Projects

The post comprehensively explains the current rating of MOSFETs in their datasheets, and helps us to understand how it is calculated by the design engineers, keeping in mind the various […]

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The above fairly good reference.


Regards, Dana.

 

[dick_freebird]

Many reliability (limiting) mechanisms behave the same whether you look at steady state or time averaged current / power. Averaging a pulse train "ratios down" the peak to a lesser number. You should also see a declaration about what duty cycle this limit is coupled to. You might see 10% or a fixed PW and freq and be left to do your own figuring regarding actual stress.

If you get 4X relief for 10X sandbagging, that's not much of a deal.

 

[andre_luis]

At the end, it's all about the heat. A continuous current will generate a temperature converging to a stable value after a short time. With a pulsed current, on the other hand. The smaller the duty cycle, due to the thermal gradient in that section of the chip, the greater the instantaneous ability of this heat to propagate in the silicon die, whose mass acts as a buffer for thermal transients. Think of an incandescent light bulb as an analogy; the filament takes time to radiate the light and goes out, it does not happen instantly.