TS3A226AE: Pressing on earphone buttons makes noises in the earphones
Part Number: TS3A227E
We are using the TS3A227E in a communication device. Clicking is heard on the receiving device when the buttons are pressed on an attached headset. Is there any way to reduce/eliminate this noise?
Thanks for sending the scope shots and schematic. It looks like you're using TS3A227E, is this correct? I edited the post to reflect this.
Could you point out where in the system you're measuring this signal in your shots? These waveforms appear to be clean, I don't see any noise, overshoot, etc., which is expected. Are you seeing any visible click/noise in any signals in your system? Could you send those scope shots?
To confirm, what is the function of the button press to the signal when you hear the click?
Could you take a scope shot of the input of the mic signal to the switch and the output at MICP?
The click/pop noise reduction feature of the switch is designed to remove the click at the insertion and removal of the connector itself.
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In reply to Kate Dickson:
Yes, we are using the TS3A227ERVAR.
The blue trace in the screen shot is MICP.
I have not found any other clicking except when the headset buttons are pressed. The audio from the audio amplifier is very clean. The audio from the microphone has some distortion depending on which brand of headset I am using. I am still tracking this down to determine if this is an issue with the headset microphone or noise in the system.
For the screen shots I was pressing the play button on the headset which the TS3A277 reports as keypress 4. There is no difference depending on which headset I test with.
I have attached more screen shots as you requested. The blue trace is MICP and the yellow trace is SLEEVE
Yes, we have noise from insertion and removal of the headset.
In reply to Randal Torgerson87:
Thank you for sending the scope shots. The mic signal appears to be passing through the switch undistorted, which is expected for this switch.
The distortion you may be hearing seems to be a system level issue. Based on the waveforms, I do not suspect any issue with the signal through the switch. Do you have any concerns about the switch's performance specifically?
Yes, the click/pop noise reduction does not see to be working.
From the data sheet "Internal isolation switches allow the TS3A227E to remove the click/pop noise that can be generated during and insertion or removal of an audio accessory."
The button noise, insertion and removal noise are not being suppressed.
The click/pop noise reduction is designed to ground the Ring2/Sleeve pin during insertion to avoid the "click" associated with the voltage difference on those pins. However, you will hear a click during insertion if there is a signal on Left/Right pins during insertion. The way to resolve this is to mute or ensure that no signal is on the L/R channels during insertion.
I do not suspect that the keypress 4 would cause a click/pop internal to the device. Can you try removing the device or shorting the signal across the device and see if you still hear the click from the button press?
I muted the audio amplifier driving TIP and RING1 when the headset is not inserted. I can still hear the pop and click on a connected device when inserting the headset and when pressing the buttons. I agree that the pop and click is not being generated inside the TS3A227E but the TS3A227E is also not suppressing the pop and click per the data sheet.
We are thinking a low pass filter on MICP may reduce the pop and click. Do you think this will be effective since the button presses are a step input? The filter would be implemented in a DSP.
Have you tried exchanging the audio jack and contact switch with new ones? Also, have you tried replacing the TS3A227E in your system with a new one?
You can certainly try the low pass filter and see if this reduces noise. Let me know if this helps.
We have several units and all have the click and pop from the headset buttons in varying volume. We have found in our testing of several headsets that the volume of the button presses vary by manufacturer and model.
Could you try disconnecting MICP entirely and describe your observations during insertion?
When MICP is disconnected from the DSP, obviously the we don't hear the noise from the transitions from the button press or release. I still see the transitions on the scope and they don't look any different from when MICP is connected to the DSP.
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