我应该将MUTE和STBY称为VSS的电压吗？

我有一个TDA7491LP设计，我似乎无法发挥功能。我跟着''

应用D类放大器电路的示例电路（数据表中的图26）。我用10V开关模式电源为放大器供电。

电路板的一些测量结果，全部参考电路公共端（SGND和PGND连接）：
3.5VSTANDBY（引脚20）在3.5VVDDPW（引脚19）和VDDS（引脚26）处的MUTE（引脚21）均为3.2V.PVCC在10VVSS（引脚36）处提供10VSVCC（引脚35）读取~6.5 VVREF（引脚34）在~1.8VSYNCLK输出（引脚25）读取~4V方波~630kHz我已将输入配置为单端模式; INNA和INNB分别通过单独的470nF电容连接到我的电路公共端。我在INNA上提供1Vp-p 1kHz正弦波。我应该看到OUTPA / OUTPN处的PWM波形，但这两个引脚组的读数都在200mV左右。完全没有PWM活动。


现在我有点困惑; SVCC称为“信号电源”，VSS称为“3.3V稳压器输出电源” - 我应该将MUTE和STBY称为VSS的电压吗？


我想更新帖子，让任何人在将来搜索我已经解决了ST帮助的问题（你的FAE是最好的！）我的问题实际上是在几个月前解决但我忘了回到这里更新线程。

我将我的电路板与ST提供的TDA7491LP评估板进行了比较，并检查了所有内容;然后我用评估板上的部分替换了输出滤波器部分，一旦我这样做，故障状态就消失了。我想我选择的LC滤波器非常差，导致输出显示为短路，这导致TDA7491LP自我保护。

我目前正在运行输出部分，与数据表中的图34相同;也就是说，我使用的是小铁氧体（BLM31PG601）而不是输出电感，使用1nF作为输出滤波电容，并使用2.2nF电容从输出的每一脚接地。
＃tda7491



以下为原文




I've got a TDA7491LP design that I cannot seem to make function. I've followed the ''

Applications Circuit for class D amplifier'' example circuit (Figure 26 on the datasheet). I'm powering the amplifier with a 10V switchmode supply.

Some measurements from the board, all referenced to the circuit common (where SGND and PGND are connected):

• MUTE (pin 21) at 3.5V
• STANDBY (pin 20) at 3.5V
• VDDPW (pin 19) and VDDS (pin 26) are both reading 3.2V.
• PVCC is supplied with 10V
• SVCC (pin 35) at ~10V
• VSS (pin 36) reads ~6.5V
• VREF (pin 34) at ~1.8V
• SYNCLK output (pin 25) reading ~4V square wave of ~630kHz
  

I've got the inputs configured in single-ended mode; INNA and INNB are each conected through individual 470nF capacitors to my circuit common. I'm supplying a 1Vp-p 1kHz sine wave on INNA.  I should be seeing a PWM waveform at OUTPA/OUTPN but both these pin sets are reading about 200mV; there is no PWM activity at all.


Now I'm a little confused; SVCC is called ''signal power supply'' and VSS is called ''3.3V regulator output referred to power supply'' -- Should I be referring MUTE and STBY to VSS's voltage?  



I wanted to update the thread and let anyone searching in the future that I have resolved the issue with ST's help (your FAEs are the best!) My issue was actually resolved months ago but I'd forgotten to come back here to update the thread.

I compared my board against the TDA7491LP eval board provided by ST and everything checked out; I then replaced my output filter section with the section from the eval board and as soon as I did this the fault condition went away. I guess my choice of LC filter was very poor and causing the output to appear as a short, which caused the TDA7491LP to protect itself.

I'm currently running the output section the same as Figure 34 in the datasheet; that is, I'm using a small ferrite (BLM31PG601) instead of an output inductor, using 1nF as the output filter capacitor, and using 2.2nF capacitors from each leg of the output to ground.  
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