SSM2529 проблема шума

SSM2529 noise issue

Активно 2 Ответы 20 Просмотры 2016-11-28 Общие вопросы

Hello,

I am working with SSM2529 but I had some problems.

1. When I play audio file sine (1khz_44100_mono_30s.wav) to test. After that I'm using OSCILOSCOPE to view on OUPUT pin (OUTP + OUTN) of SM2529. It's not sine wave, I see square wave (rising1111ws450.png).

2. When I adjust volume louder (maximum) then speaker is quite noise.

I also attach audio file and wave form which I capture from OSC.

I attach SSM2529 schematic connection. As for the load, I'm using speaker (8ohm, 2W).

Thank you

attachments.zip


guest replied
2 Years

Hello Trez,

The SSM2529 is Class D audio amplifier. To achieve the high efficiency Class-D amplifier output stage typically switches between PVDD and GND only. The waveform at the output will be Pulse Density Modulated by the input audio signal. The speaker outputs are low Pass filtered if you want to observe convectional Analog sine wave. If you would like to see the sinewave then you will need to add the low pass filter at the output to remove the switching frequency. The outputs look normal in your scope capture they are switching between PVDD/ GND.

Please note the amplifier output is differential i.e. the load is floating. The SSM2529 is filterless amplifier and hence does not need passive low pass filter for applications where the speaker is close to amplifier. It uses the speaker inductance to reduce the current ripple and speaker acts as low pass filter in real application. The low pass filter is only required for audio measurement purpose or for applications requiring the long speaker cables to reduce the EMI.

Regards

Rajeev  

guest replied
2 Years

Hello,

It is a Class D amplifier. This is the proper output. Read this on Wikipedia. It does a great job at explaining this.

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