为什么tda7498e D类放大器芯片处于待机状态？

经过几天测试一堆吹制芯片后，我可以确认，如果你用配置为单声道模式的芯片切换待机信号并将音频应用到芯片上，芯片可能会被破坏。我运行了以下测试：
芯片配置：
1.模式引脚连接到VDDS（单声道模式），
2.根据数据手册，OUTA和OUTB引脚并联连接
3.电源电压设置为+ 35V
测试程序
1. 1khz信号施加到芯片INPA输入，输出电平设置为约80％，无输出负载
2.待机信号已激活
3.等待1-4秒之间的随机时间段
4。
待机信号已停用
5.等待1-4秒之间的随机时间段
4.转到上面的第2步
通常芯片在10分钟内吹。您可以使用静音信号重复测试并且芯片很好（我让测试运行12小时且没有损坏）。
我现在运行以下测试：
1. 1khz信号施加到芯片INPA输入，输出电平设置为约80％，无输出负载
2.静音信号已激活
3.等一下。
4.待机信号激活
5.等待1-4秒之间的随机时间段
6。
待机信号已停用
7.等一下。
8.静音信号已激活
9.等待1-4秒之间的随机时间段
10.转到上面的第2步
该测试已经运行了1个多小时而没有损坏芯片，所以看起来如果芯片静音，同时将芯片带入和退出待机状态，它可以正常工作。我不知道在这个阶段你必须等待多长时间才能改变静音和待机信号（目前在我上面的测试中是1秒）。
一般来说，我发现ST文档非常差，ST对各种信号的细节很少，包括Diag，Mute，Standby，Synclk和Rosc。没有详细说明示例电路上显示的静音和备用引脚上所需的电阻。后者发现（通过ST工程师）需要至少30k的电阻值来保证其工作。没有提到电容器（例如它们是否需要，如果是这样，它们的最小值和最大值是多少？）。
注意我还没有通过社区，他们的技术支持网站或通过Braemac得到ST的答复，所以看起来ST技术支持和他们的文档一样糟糕。遗憾的是，芯片在其他方面表现良好。在使用任何其他ST部件之前我会做两次。
问候，
休



以下为原文




After several days of testing a a pile of blown chips I can confirm that if you switch the standby signal with the chip configured for mono mode with audio applied to the chip the chip may be destroyed. I ran the following test:

Chip configuration:

1. Mode pin tied to VDDS (mono mode),

2. OUTA and OUTB pins wired in parallel as per data sheet

3. Supply voltage set to +35V

Test Procedure
1. 1khz signal applied to the chip INPA input, output level set to about 80%, no output load
2. Standby signal activated
3. Wait a random time period between 1-4 seconds
4.
Standby signal deactivated

5. Wait a random time period between 1-4 seconds
4. Go to step 2 above
Typically the chip blows within 10min. You can repeat the test with the mute signal and the chip is fine (I left the test running for 12 hrs with no damage).
I now running the following test:
1. 1khz signal applied to the chip INPA input, output level set to about 80%, no output load
2. Mute signal activated
3. Wait 1 second.
4. Standby signal activated
5. Wait a random time period between 1-4 seconds
6.
Standby signal deactivated

7. Wait 1 second.

8. Mute signal deactived

9. Wait a random time period between 1-4 seconds
10. Go to step 2 above
This test has been running for over 1 hour with no damage to the chip so it looks like if the chip is muted while taking the chip in and out of standby it works ok. I have no idea at this stage how long you must wait between changing the mute and standby signals (currently 1 sec in my test above).
In general I've found the ST documentation very poor and ST give very little detail on the various signals including Diag, Mute, Standby, Synclk and Rosc. No details are given on the required resistors on the mute and standby pins shown on the example circuit. I latter found out (via an ST engineer) a resistor value of at least 30k is required to guarantee its operation. No mention is made of the capacitors (e.g. are they required and if so what are they for and what is the min and max value?).
Note I'm yet to have a reply from ST via the community, their technical support website or via Braemac so it seems the ST technical support is as bad as their documentation. A pity as the chip otherwise has performed well. I will thing twice before using any other ST parts.
Regards,
Hugh

嗨休，
非常感谢您的调查！
我想知道，在立体声模式下工作，保持MODE引脚始终与GROUND相连，开启音乐播放时仍然存在吹制芯片的风险。
只是要知道在立体声模式下永久运行芯片时，您发现的漏洞是否仍然存在。
最好的rgds，
詹尼



以下为原文




Hi Hugh,
many thanks for your investigations !
I wonder if, operating in stereo mode, keeping MODE pin always tied to GROUND, there’s still the risk to blow the chip when switching on with music playing.
Just to know if the vulnerability you found is still present when running the chip permanently in stereo mode.
Best rgds,
Gianni

嗨Gianni，
在立体声模式下应该没问题。在单声道模式下，L和R输出并联连接，如果它们彼此不同步，它们将相互短路。
我进行了一项测试，将放大器放入静音约100毫秒，然后再将其置于待机状态，然后在取出待机状态后取消静音100毫秒。每个周期平均约为5秒。它运行了2天以上没有问题所以这似乎解决了这个问题。
例如。在单声道模式下，除非静音信号有效，否则不会改变待机信号的状态。
干杯，
休



以下为原文




Hi Gianni,
Should be fine in stereo mode. In mono mode the L and R outputs are connected in parallel and if they are not in sync with each other they will short each other out.
I ran a test where the amp was put into mute about 100msec before putting it into standby, then unmuted it 100msec after taking in out of standby. Each cycle was about 5sec on average. It ran for over 2 days with no issues so this seems to fix the problem.
E.g. in mono mode do not change the state of the standby signal unless the mute signal is active.
Cheers,
Hugh

好吧，所以我会远离单声道模式（在立体声模式下对我来说足够的力量）我应该安全...
TDA7498E
 是我最喜欢的芯片，因为我喜欢原生的BTL设计，以避免总线泵送，但同时，我有点担心一些突然失败的报告。现在我明白很多人在单声道模式下使用这个芯片，也许是所有这些失败的最可能原因是你发现的问题。
非常感谢！
G。



以下为原文




Ok Hugh, so I will stay away from mono mode (enough power for me in stereo mode) and I should be safe ...

TDA7498E
was my favourite chip because I liked the native BTL design to avoid bus pumping but, at the same time, I was a little bit worried about some reports of sudden failure.Now I understand that many people use this chip in mono mode and maybe the most likely cause of all these failures is about the problem you have discovered.
Many thanks again !
g.