takashiki 发表于 2017-5-25 05:40
无论什么样的电路，至少要满足欧姆定律吧。

5V供电，8欧负载，满打满算全部转换，功率P=U*U/R=5*5/8=3.1 ...

非常感谢，方案3是比较好的选择

NS4125
https://www.amobbs.com/forum.php?mod=attachment&aid=Mzc0NDYyfGI1MzllMjg0MjEyNmQ4ZWVkYWI2ZWEzZmZmNzQ2ZTEwfDE1NzU5MjkxMzA%3D&request=yes&_f=.pdf
Features
  Non-clip control to suppress output clipping
  Filterless Class-D operation
  High efficiency up to 80%(8Ω load,Po=7W,PVcc=12V)
  Wide Supply Voltage Range Allows Operation from 5 V to 12 V into    8-Ω Stereo Load
  Wide Supply Voltage Range Allows Operation from 5 V to 9 V into    4-Ω Stereo Load
  Output power at 12V supply
                7W×2 (8Ω load, 1% THD+N,BTL Output)
                8.5W×2 (8Ω load, 10% THD+N,BTL Output)
                14W (4Ω load, 1% THD+N,PBTL Output)
                17W (4Ω load, 10% THD+N,PBTL Output)
  Output power at 9V supply
                4W×2 (8Ω load, 1% THD+N,BTL Output)
                5W×2 (8Ω load, 10% THD+N,BTL Output)
                6W×2 (4Ω load, 1% THD+N,BTL Output)
                7.5W×2 (4Ω load, 10% THD+N,BTL Output)
                8W (4Ω load, 1% THD+N,PBTL Output)
                10W (4Ω load, 10% THD+N,PBTL Output)
  Low shutdown current: 1μA (typical)
  Short-circuit & thermal protection
  Packages: TSSOP-24