Reading 12bits absolute encoder

Hello,
I’m new here.
I’m on a project to use 2 12bits absolute rotary encoders.
I manage to read them using oversampling in order to try to recover the 12bits precision using the 10bit Arduino embedded ADC.
The next step would be to use a real 12bits ADC. I bought one from grove/seeed. But it is I2c. I bought the grove a2c shield.
Here is the problem how to connect the encoder to the 12bits ADC as it is I2c and the sensor has no clock ,just a data pin sending Analog voltage values from 0 to 5 ?
Is that even possible ?

I2C ADC:
https://www.seeedstudio.com/Grove-I2C-ADC-p-1580.html
encoder:

Can you share a datasheet for the encoder? What is a2c?

sorry i mean I2c not a2c :o

Sensor

Connect the analog output of the encoder to the analog input of the ADC. The ADC will output the reading through I2C. This page has some info and code for the ADC.

To read the 12 bits encoder you might need a 16 bits ADC as there will always be some noise...

Check- ADS1115 16-Bit ADC - 4 Channel with Programmable Gain Amplifier : ID 1085 : $14.95 : Adafruit Industries, Unique & fun DIY electronics and kits

Thank you for your feedback, it helps.
I'm still playing with oversampling on the inboard 10bits ADC and i'm getting decent result.
I understand that 16 bits will give me the best value and it's just 5$ more.
i'll oder that piece and try it out if I manage to make the I2C - analog voltage ..work.

I'm not sure i understand regarding the connecting . I have 4 pins one I2C and 1 on alag :
shall I simply connect the analog output to the white data pin from the ADC ?

See this page for the Grove analog (input) and Grove I2C (output) connector pinout.