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  • TI Thinks Resolved

About using comparator to detect tip pin

Hi,

Customer wants to detect audio jack insertion with the following configuration.

4pin earphone jack "TIP pin"Comparator IN / Comparator OUTTS3A227E DET TRIGER pin

Customer's available earphonejack is a 4 pin product.
For this reason, there is no switch for detecting jack insertion in the jack itself.

I got the following question from the customer.
・Is there a problem by connecting the earphone jack tip pin directly to the input of the comparator?
・Could you tell me the recommended comparator.
 Device image is below.
 datasheets.maximintegrated.com/.../MAX9060-MAX9064.pdf

I look forward to hearing from you.

Best Regards,
Yusuke/Japan Disty

  • Yusuke,

    You cannot connect the DET_TRIGGER pin of the TS3A227E to a node that has audio signal like the tip pin.  The DET_TRIGGER pin has an internal pull up resistor that would pull up the audio signal to VDD. 

     

    A comparator or any other GPIO can be used to control the DET_TRIGGER pin of the TS3A227E but it should not interfere with any audio signal on a tip pin.

     

    If you use the audio jack connector below you could have the comparator connected to pin 5 so that when a headset is inserted the switch in the jack opens and allows Vdd to pull up the node above the threshold of the comparator to drive the DET_TRIGGER pin low. 

    The concern in this configuration is making sure the pull down resistor on pin 3 doesn’t interfere with the microphone signal bias. 

    Thank you,

    Adam

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