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 this

 

hi hoy.
Consider the heat dissipation of pulsed versus continuous conduction.
E

 

A short pulse will cease before the die gets too hot but continuous current makes the die warmer and warmer over a brief time until it fails.

 

A short pulse will cease before the die gets too hot but continuous current makes the die warmer and warmer over a brief time until it fails.

Or until it reaches thermal equilibrium at a safe temperature.

 

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 this

Have you ever picked up something like a baked potato from an oven where you could pick it up long enough to quickly move it from the pan to a plate, but that there was no way that you could stand there and hold it for much longer than that without suffering painful burns to your hands? It's the same thing. There is a maximum temperature potato that you can hold indefinitely and there is a higher maximum temperature potato that you can hold at least momentarily. Between those two temperatures, you can hold the potato, but only for a short period of time.

The same thing with the current in most electronic devices, except that most data sheets only show the max continuous current because the device is not expected to be operated in any kind of pulsed operation. But transistors are often operated that way, so the spec sheets contain more information about operating them that way.