CLASSD的功耗与DCDC的问题！求解啊

cocacolahj · 发表于 2009-6-25 13:57:13

一块CLASSD，预想9V下输出5w的功率到8欧的speaker上，一块dcdc给它供电，dcdc的最大输出电流需要多少啊，，关于这个最简单的问题还不能很明确，我现在采用的是9V下输出max current 800mA的够吗？
我选择CLASSD看图表在12V 8欧姆 5w的输出功率下，芯片的supply current 是500mA左右。（9V应supply current应该更低？？）
按照datasheet上理解classD的效率在80%左右，其实就是说12V下 dcdc提供的总功率是12*0.5 是6w左右，输出是5w，加载在8欧的阻抗上，电流是多少?直接P/R 开个根号？
这样子似乎够了，可是FAE却说不够？？

cocacolahj · 发表于 2009-6-25 14:06:38

自己顶

cocacolahj · 发表于 2009-7-25 22:41:35

汗没人看

millwood0 · 发表于 2009-7-26 05:55:49

"dcdc的最大输出电流需要多少啊"

it depends on many factors. But under some crude assumptions, the current is roughly determined by Vcc divided by the sum of the speaker impedance and the impedance of the R/C network at the working frequency of the Class D amplifier.

for worst case analysis, just use Vcc / Rload.

it is VERY VERY difficult to design a dc/dc converter to power a class D amp, because of that.

CLASSD的功耗与DCDC的问题！求解啊

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