TRS headphone output socket that may be used with a TS mono jack: how to prevent short to ground?

Question

I'm using a TPA6132 headphone amplifier connected to a stereo (TRS) output socket. In my application, the output will usually be used as a line output, and only occasionally with headphones. The audio is actually mono, so typically a TS jack will be plugged in when used as a line output, shorting the ring contact to ground.

The TPA6132 has short circuit protection, but draws over 100 mA in this case, which I would like to avoid, seeing as it would be in this mode most of the time. I've tried a MAX97220, which looks a bit better in this regard, but still draws around 25 mA.

There are chips like the TS3A226 that do ground detection and can disconnect the ring contact, but the ones I could find are made for 4 pin or 5 pin TRRS/TRRRS headset jacks.

Is there any good way to achieve the same kind of ground sensing and disconnection using discrete components, or is there any chip that does what I'm looking for?

I'm also open to alternative suggestions. I've thought about adding series resistors in the low double digit ohm range, but that's similarly wasteful.

Answer 1

A series resistor in tip and ring wires may be enough to keep the short circuit current acceptably low and the headphones can still get enough signal power. It, of course, depends on the used headphones. Test.

Another possible solution is to leave the jack sleeve terminal unconnected. Use the ring contact as your GND. The headphones get opposite phase signals, but check if you can still accept it. It wouldn't work with speakers, but it can work with headphones.

The 3rd easy solution is to use an adapter. That's already suggested in comments by others. Make the jack wiring for mono plug, so forgetting the adapter doesn't cause a short circuit.

LATE ADDITION

Unwanted consequence if you use the "sleeve unconnected" trick in a machine which is made for others: One day someone inserts a stereo plug to get the signal to his amp. The result can be a super loud noise which can be dangerous if the amp has high power. At least add a warning disclaimer. Try to connect the sleeve terminal to the ground with a 1kOhm resistor to reduce the rumble. It probably doesn't reduce the headphone volume too much.