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Original question:

LM4871: Case CS0581107 has been Updated - technical problems--LNKDH-1074291 - Flex ==>TI MPN#LM4871MX/NOPB

LM4871: LM4871 has a pop sound when enable shutdown please help check if could eliminate

Zoe Yang
Intellectual 2210 points
Part Number: LM4871
Other Parts Discussed in Thread: TPA6211A1

Dear experts,

My customer use the LM4871MX to drive a speaker, and test the speaker will have a POP sound at the moment of playback.

Testing conditions:

1. There is a POP sound during normal playback
2. Shorten the input and tie it to the  ground. Enable SHUTDOWN (pull the flying line, then pull it down), there is still a POP sound
3. The BYPASS capacitor can be adjustable to improve the sound, but cannot be eliminated.

The external circuit is shown as followed.  Ch3 is VO+, Ch4 is VO-.

Please let me know what can be done to solve this problem, thank you.

  • 0
    TI__Guru** 102045 points

    Hi Zoe,

    First thing I would check is if the device is properly working for this configuration. From data sheet the typical application circuit shows single-ended input, being IN+ shorted to bypass pin, so that output signal of the first stage to input of second stage is the exact same.
    Notice this is not a fully-differential amplifier like TPA6211A1 or similar. Please try using the same circuit as Figure 3 from data sheet.

    Best regards,
    -Ivan Salazar
    Applications Engineer