LP8860-Q1: LP8860-Q1 Thermal PAD

Hi Fukazawa-san,

Yes, thermal pad shape of LP8860 is as shown in the picture in your question.

Footprint for thermal pad should be bigger than the pad size for max efficiency.

Max thermal pad size from datasheet is 2.86mm for flat edge, and actually you can make it 3.1mm or longer for square shape.

Polygon size on LP8860 EVM for thermal pad connection is almost 5mm*5mm.

Hope this helps,

Hello,Sung-san

Thank you for your reply.

With your kind explanation, I understood that the thermal pad can be designed with a 3.1 mm × 3.1 mm square.

Is there any recognition of me?

Best,Regars

Fukazawa

Hi Fukazawa-san,

Yes, you can design thermal pad footprint as small as 3.1mmx3.1mm.

I would even increase the size like 4mmx4mm to consider alignment and extra margin.

Hope this helps,

Hi Fukazawa-san,

There are not that many restrictions for clearance of vias.

 Count of thermal via will be more important. LP8860 EVM has a lot of thermal vias to dissipate heat to GND plane.

You can also calculate thermal impedance of vias by this equation and use it to estimate temperature increase by power dissipation on IC.

Hi Fukazawa-san,

It seem OK enough for this package. Making 4mm*4mm square copper will be good enough.

And using vias an many as possible will help dissipating heat though it may increase PCB cost.

Hope this helps,