About THS1408's package problem

    I use THS1408 which have powerpad in my project,when I want to layout, I confused with connect of powerpad,In the datasheet and SLMA002 , Just say the pad should connect  to internal layer with via,But the internal is power layer or digital GND or analog GND is not described。

   Please resolute this problem, thanks very much. 

Please download SLMA002 "PowerPAD™ Thermally Enhanced Package"

http://www.ti.com.cn/general/cn/docs/lit/getliterature.tsp?baseLiteratureNumber=slma002&fileType=pdf&keyMatch=slma002&tisearch=Search-CN-Everything

Please soldering the exposed thermal pad to a GND plane on the PCB which provides good thermal performance.