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TS3A226AE: 3.5mm to USB-C?

Leith Al-Saaigh
Prodigy 20 points
Part Number: TS3A226AE

Hi,

Im interested to know if there is a way to use the TS3A226AE or other component in a headphone. 

I came a cross this blog post when I was searching the web.

https://e2e.ti.com/blogs_/b/analogwire/posts/usb-type-c-why-mobile-phone-designers-should-remove-the-audio-jacks-from-our-phones

Here the idea is to use USB-C to 3.5mm but what Im looking for is the opposite. 

3.5mm at the host and then a dongle to USB-C to a headphone. Is that possible with TS3A226AE or other component? 

Looking forward some more insight in this topic. 

Thank you

/Leith

  • 0
    TI__Genius 10974 points

    Hi Leith,

    We are currently on holiday and will get back to you on 9/6.

    Thanks!
    Bryan

  • 0
    TI__Mastermind 28028 points

    Hey Leith,

    I'm a little curious about the use case here. I suppose if you have an older device that has a audio jack but no USB-C input and also have a pair of newer USB-C headphones, this may be a fix. I can definitely see it as a fix for a pretty niche scenario but don't see this being useful for too far into the future as more and more devices are opting out of the audio jacks only approach and either have only USB-C or both. Additionally, a USB-A to USB-C would be a better solution for this; Although my understanding is that this technically violates USB-C specifications. I'm not an expert here with regards to the USB standards but I believe the violation has to do with the required internal resistors for USB-C to USB-A adapters to allow for faster charging (lowering the resistance allowed for up to 3A support, well above the spec recommend 0.9A). I believe you may run into technical violations of the USB-C specifications with this use case you're proposing as well along with some other system level considerations which have deterred others from making such a device. 

    The tricky part here would be how to convert that signal from analog to digital. The audio jack won't provide enough voltage for the digital logic that would be required for such a task. You would probably be required to use an external power source, like a battery bank. So the device itself now would start getting quite pricey, large and complex. So bottom line, it would be do-able but would probably be easier if you had a USB-A part to just use an adapter there instead.

    That being said, if you still went through with creating such a dongle, with regards to actually detecting the jack input, in actuality I believe this would just be the generic use case. You wouldn't detect the 3.5mm in the dongle itself but the host side should be able to do the detection and the signals should be rerouted accordingly. What the proposed dongle should be doing is just rerouting the USB-C single to the correct audio jack location so that whatever is plugged is detected there and the audio signals can be sent to the proper location depending on the configuration. You would also need a 'female' USB-C input which you don't see much of this not integrated in the device but doesn't mean this can't be created for this specific use case. 

    Thanks,
    Rami

  • 0 in reply to Rami Mooti1
    Prodigy 20 points

    Hi Rami,

    Thank you for your promt reply. A lot of toughtful ideas. 

    Let me explain a little more about the idea. So I work at a company that design headphones and we are think about a concept where w remove the 3.5 jack. But still want to offer the possibilty for customers of the headphone to be able to connect it to an onlder device with  the only option a 3.5mm jack. It is a battery powered headphone with the BT option as well. So I assume that the battery power is required to handle the analog signal. 

    It doesnt need to be a dongle. But yeah something with USB-C and 3.5mm, could be custom just to enable the detection part. 

    I aggre with you that the idea here violates the USB-C spec. They are offering the new "Analog Device Class 3.0" that enables digital audio transfer over USB-C to USB-C. That part might be tricky to combine with the analog input among other spec violations. 

    I have read a lot online and the closest I could found was this blog post I already shared. I was about to give up on this but tought that I could check with you guys if you could guide me in any direction. 

    With some more additional information do you think this is a dead case or possible? I just want to make sure that I have not missed anything obvious. 

    Thanks in advance and looking forward to your reply.

    /Leith

  • 0 in reply to Leith Al-Saaigh
    TI__Mastermind 28028 points

    Hey Leith,

    This is definitely an interesting idea and has been a good thinking exercise on my end but I'm not exactly in the business of giving you advice on what direction your company should take here so I wouldn't hold my words as gold. I do think though that it is certainly possible to make such a device with an external supply (external from the USB-C / peripheral aka a battery since port won't be able to provide power) and some logic (an ADC would probably be used as well). Now whether you believe your company can do this in a smaller, convenient and effective way and be worthwhile would leave the scope of the support I can provide here though.

    Thanks,
    Rami