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Hi Lina,
I reviewed the SCH and found that the input capacitors are not balanced. 1uF capacitor (C299) is used on RINN pin but 2.2uF (C298) is used on RINP pin. The same is the left channel. Please use 1uF capacitors for both INN and INP.
Best regards,
Shawn Zheng
Hi Lina,
Please let me clearify your question: when apply a DC voltage on the input, you heard white noise, right? How much is the DC volage? And what if apply a AC signal (e.g. 1kHz sinewave)? Is the output is expected? Where is the input signal from? DAC/Codec or AP instrument?
Why do you apply a DC signal on the amp input? Actually DC sigal is harmful to speaker, sometimes damges it. When the issue occur, did you check the FAULTZ pin? High or Low? DC FAULT could be triggered if the input DC exceeds the DC detect THR. Did you check the waveform on the output pins? The PWM is still switching or not? What about the measured signal on the speaker?
Best regards,
Shawn Zheng
hi shawn,
input is 0hz file, or one audio signal, and adjust voice to the minimum, and then you can hear "sasa" noise, if you use 1khz sinewave, also have this sound, and we can't measure it by oscilloscope, pwm is still switch, output signal also is normal, FAULTZ pin is also normal. speaker side signal also is normal.
Hi Lina,
So this issue actually not related to the input source. The issue occurs when the volume is low. What if you drive MUTE pin to a High voltage? Does the noise still exist?
Did you check the noise floor on the output signal?
When the issue occurs, did you measure the waveform on the input pins? What if you disconnect the input cable and connect RLINP/LINP port in the SCH to GND?
Best regards,
Shawn Zheng
hi Shawn,
customer have done below action,1. input signal short grond, 2. change battery to power supplier( before Adapter), 3. change to frequency to 400khz, 4. only PA work, noise is still occur, what do you other comment?
Hi Lina,
So the power supply applied on the device is clear, right? Did you measure the ripple on the PVCC/AVCC?
During this measurement, please power down all of the other devices in case the noise from them is coupled to audio amp.
Can you show me the 'abnormal' output signal? With input pins conected to GND through 1uF capacitors, the expected output signal is 50% duty-cycle PWM waveform.
Is this issue related the board or device? In another word, all of your boards show this issue or only part of them? What if substitute the device on the bad board with a new device? Please also help to check the soldering on the board.
TPA3118D2 is very widely used in the market and I never heard of this noise isse. I believe this is an application issue.
Best regards,
Shawn Zheng
yes, power is clear, PVCC/AVCC ripple is drop to 190mv at present, they measurement when they power down other device except of TPA3118D2, in addition, this issue exist on the all of board, so we can't fix issue on the device or board. output signal duty cycle is 49.13%, They need to be close to speakers from less than 2 cm to hear noise, and their THD is also small , is 0.8%.
Hi Lina,
What if you drive the pin #12(MUTE) to high? Can you still hear the noise please? Your output waveform looks no problem, but 0.8%% THD is a little high. Did you measure the noise on the GND?
Best regards,
Shawn Zheng
hi shawn,
customer said if they connect input signal (4 signal ) to ground without through cap, there is no noise, if through cap, noise occur again.
in addition, how to test ground noise use oscilloscope, thanks.
Hi Ling&Yongxue,
If the noise still exists even if MUTE pin is pulled to high, I believe the noise is not caused by power supply or input circuit. Becasue when MUTE is pulled to high, the PWM stops switching and there is actually no output signal. So please help to check the output circuit/components and speaker line, make sure there is no obvious noise coupled to the output. Please try to use short speaker line and short trace on board to speaker.
When INPL and INNL are connected to GND directly(without DC capacitors), the device is set to PBTL. In this case, INN and INP are actually shorted together. So there is only common noise on them, and no noise is heard from the speaker.
Best regards,
Shawn Zheng
Hi Ling&Yongxue,
Plesase let us know if you have any other question here. Please help to close it if you don't more other question. Thank you.
Best regards,
Shawn Zheng
hi shawn, customer haven't close this issue, they want to call you directly, whether you are convenient, if you can, could you send me your call number by email.
