TS3A227E: Audio forum

Hi Randal,

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.

Thanks!

Kate

Kate,

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.

Randy

Hi Randy,

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?

Best regards,
Kate

Kate,

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.

Randy

Hi Randy,

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?

Thanks,
Kate

Kate,

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.

Randy

Hi Randy,

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.

Thanks,
Kate

Kate,

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.

Randy

Hi Randy,

Could you try disconnecting MICP entirely and describe your observations during insertion?

Thanks,
Kate

Kate,

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. 

Randy

Hi Randy,

Great to hear from you again.

I am looking at the MICP output in your schematic. Could you let me know/measure what your MICBIAS level is? Why have you placed C22 here?

For reference, take a look at the MICP output from Figure 19, Typical Application Schematic, in the datasheet:

Regards,
Kate

Kate,

C3 (an AC coupling capacitor) on Figure 19 is not C22 on my schematic.  C22 is a bulk capacitor for the output of a REF2925AIDBZR which is ~1 inch from    C22 and R14 which are placed close to pin 6 of the TS3A227ERVAR. The AC coupling capacitor is placed close to the DSP input and is not shown.

Randy

Hi Randy,

Thanks for your patience as I try to isolate the issue. 

Randal Torgerson87 said:

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. 

The switch is not designed to suppress noise from button presses on the headset. You can try to troubleshoot this in your system.

The click/pop reduction feature of TS3A227E is designed to reduce noise from insertion and removal of the plug. If you are experiencing noise during insertion, I would be happy to help you troubleshoot that issue.

Please send audio, video, and scope shots of the following scenarios so that I can better understand what you are experiencing.

• Do you hear and see noise while inserting the plug?
• Mute the signal from the DSP, insert the plug again. Do you still observe noise?
• Disconnect MICP from the DSP. What are your observations when inserting the plug?

Additionally, have you tried changing the audio jack with a new one?

Best regards,
Kate