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LM4766: Click/Pop noise reduction

Part Number: LM4766
Other Parts Discussed in Thread: TPA3126D2

Dear Specialists,

My customer is testing LM4766T and has a question.

I would be grateful if you could advise.

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A click / pop sound is generated when turning the power on or off.

It is not related to ON / OFF of the mute of the amplifier.

In the data sheet p16 of FIGURE 6 of CLICKS and POPS, it is described that it can be improved by adjusting RBI.

Could you tell me the specific adjustment method and the range of each allowable resistance?

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I appreciate your great help in advance.

Best regards,

Shinichi

電源投入時とOFF時にアンプAのミュートの可否に関係なく
クリック/ポップ音が発生しています。
R22,26,27の調整にて改善できる旨がデータシートにp16にありますが
具体的な調整方法と許容される各抵抗値の目安をお教えいただけるでしょうか。

  • Hi Shinichi-san,
    In single-supply mode, pop noise during power-up and power-down is an issue. Please use the recommended circuit shown in the Figure 6 in the datasheet as much as possible to minimize the pop noise. The input/output coupling caps and the negative feedback make the circuit complex. You could try to adapt the RBI slightly to see if there is any improvement.
    Unfortunately the support available for this device is very limited as there is no evaluation board for testing and the documentation is reduced. Please refer to our new class-d product TPA3126D2, which has much better performance and efficiency.
    Best regards,
    Shawn Zheng
  • Hi Shawn,

    Thank you for your reply.

    I under stand you don't have EVM and cannot confirm the value of RBI.

    I'll tell this situation to the customer and make him check it out.

    I appreciate your great help.

    Best regards,
    Shinichi