Electrical – SOIC-8-EP instead of SOIC-8 is that okey


I have a FDS4559 which is a SOIC-8 package.
However I wonder if i could use a SOIC-8-EP instead and put some thermal compound between the PCB and the component for some extra cooling and use the PCB as a heatsink.

I don't think there will be any consequences if the pin number 9 is connected to the ground plane for extra cooling.

However I ask this question to verify that I've nothing to worry about?

Best regards

Best Answer

If you mount a regular SOIC-8 part on a SOIC-8 footprint with a copper pad intended to connect to the thermal pad of a SOIC-8-EP, it won't cause electrical problems.

But it won't improve the thermal performance much either, because the thermal resistance of the plastic of the chip package is much higher than the thermal resistance of the copper in the lead frame.

Most of the heat will still have to be removed through the copper lead frame, not the plastic body.

It would be better to use the copper area to connect to the drain pins, as shown in note 1 on page 3 in the datasheet:

enter image description here