Value of drain current

[pona]

Why drain current becomes max at start of plateau region and remain const after that? What could be the reason if it does not remain const during plateau region but keeps on increasing? I have simulated an inrush current limiter circuit from Motorola application note using IRF5140 and Id continues incresing till it reaches end of plateau region.

 

[randell_xtian]

it is becoz, the device is drawn maximum current at a start-up. When it reaches saturation point (operation point) it will down and become steady. if it is continue to rise, the device is not yet on saturation point (soft start condition) gradually increasing.