Decrease power dissipation of IRF9540

[ata90]

According to the practical testing on IRF9540,
Load = 1.8 ohm
Vsg = 8.4 V
Vsd = 0.61 V
Id = 3.56 A
then Power dissipation of IRF9540 is Vsd*Id = 2.17 W.
is there any solution to reduce Vsd in order to decrease power dissipation of IRF9540?

 

[dick_freebird]

It would probably be reasonable to call Rds(on) constant
up to a few volts Vds and down to 0 Vds. But you will
need to determine behavior at higher Vds as well, which
probably wants pulsed mode measurement.

 

[ata90]

It would probably be reasonable to call Rds(on) constant
up to a few volts Vds and down to 0 Vds. But you will
need to determine behavior at higher Vds as well, which
probably wants pulsed mode measurement.

So, what's your suggestion?

 

[SherpaDoug]

It depends on what you are trying to accomplish. One way to reduce Vsd and reduce heating would be to parallel another IRF9540. Switching from a Siliconix brand to an IRF brand IRF9540 would reduce Rds(on) as well. Going to a lower voltage MOSFET would get you lower Rds(on) for the same size package.

 

[ata90]

is it usual for similar usage that we have 2W power dissipation on PMOS or this amount of power dissipation is more than usual values of similar usage?

 

[RCinFLA]

Take the gate drive to about -7 vdc. The Rds-On will depend on device temp based on your heat sinking but with greater gate bias you should knock the dissipation down by factor of three or more.