Teensy 3.2 to ATtiny with 16-bit ADC?

Hi all,

I know that Teensy has their own forum, but I thought this question may still be relevant here.

I'm currently working on my first project with Teensy. The subsystem of my project that this post is concerned with basically needs to retrieve analog readings from an oxygen sensor (which outputs 7-12 mV) and do some calculations, then transmit this information via RF communication to another piece of the system.

The reason I chose the Teensy 3.2 for this project is that I needed a 16-bit ADC to get precise readings from my oxygen sensor. I am now nearing completion of the coding for this project and I'm ready to shrink it down.

The only pins being used on the Teensy 3.2 are: pin 2: button for waking up/putting to sleep (snooze) pin 12: RF transmitter pin 22: Oxygen sensor Vin AGND

Right now it seems that the best route is to program an ATtiny 85 with the Teensy, and put that on a PCB. If this is false, please let me know. My problem with this, though, is that the ADC on the ATtiny 85 is 10-bit. I need 16-bit.

What are my options here? Are there other chips similar to the ATtiny that have a 16-bit ADC? Or do I need to get an external 16-bit ADC and link that to the ATtiny?

Thanks in advance, Blake