目前做的电路板没有大面积覆铜，单点接地 发现纹波很大，插了众多资料说可能是走线问题
在芯片的应用手册里关于PCB LAYOUT OPTIMIZATION里讲到
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.走线就是要宽 走线要短 ，外围器件和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.这里讲到了用大面积覆铜 或者单点地 不是互相矛盾的么？
