目前做的電路板沒有大面積覆銅，單點(diǎn)接地 發(fā)現(xiàn)紋波很大，插了眾多資料說(shuō)可能是走線問(wèn)題 

在芯片的應(yīng)用手冊(cè)里關(guān)于PCB LAYOUT OPTIMIZATION里講到

As in any switching regulator,layout is very important.rapidly switching currents associated with wiring inductance can generate voltage transients which can cause problems.For minimal inductance and ground loops,the printed circuit traces

should be as wide and short as possible on the pcb.走線就是要寬 走線要短 ，外圍器件和DCDC芯片要近 

For best results ，external components should be located as close to the switcher IC as possible using ground plane construction or single point gronding.這里講到了用大面積覆銅 或者單點(diǎn)地 不是互相矛盾的么？