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I am having difficulty with a headphone plugged in and speaker mute configuration.

I am using the SJ-3524-SMT-TR headphone jack and the TPA711DGN audio amplifier IC. What circuitry should I use with the detect pin of the headphone jack in order to complete my circuit?

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Here's the pinout from the datasheet. You are interested in the right-side of the table.

enter image description here

Looking at the schematic of the connector, it can be understood that the pin-4 is normally connected to tip (pin-2), and is disconnected when the mating plug is inserted.

Here's your requirements:

  • direct the signal to the headphone when it's inserted
  • direct the signal to the speaker when the headphone is unplugged

In order to achieve this,

  • The signal should go to pin-2,
  • and exit through pin-4 to speaker amplifier.

enter image description here

When there's no headphone plug is present, the signal goes through normally-closed pin-2 and pin-4 to power amplifier. When the plug is inserted into the headphone jack, the signal will still be on the pin-2 therefore the headphone will get the signal. But since the pin-4 will be disconnected, the PA's input will be disconnected from the source. This will make the speaker muted. A proper pull-down resistor is needed across the PA's input in order to achieve proper mute and prevent humming/buzzing.

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