Hello,
I'm building a circuit that is supposed to measure light intensity using photodiode.
For transimpedance amplifier I'm using the following circuit with Vbias set to 1.2V.
![](https://i.imgur.com/hiRbFYY.png)
For digitization I want to use MCP3561 24 bit Pseudo-Differential ADC (
https://ww1.microchip.com/downloads/en/DeviceDoc/MCP3561.2.4R-Data-Sheet-DS200006391A.pdf).
![](https://i.imgur.com/ZLeW5D6.png)
When there is not light, amplifier will output biasing voltage so I wanted to set up the ADC to measure difference between output and Vbias.
Ideally Vbias would correspond to code 0 and Vbias + 2V would correspond to the highest code.
My understanding is that I need to connect Vbias to Vin- and output from the amplifier to the Vin+. However I still have some troubles understanding how to connect reference voltages. This ADC has positive reference voltage and negative reference voltage.
My question is what is negative reference voltage used for and how I'm supposed to connect the reference voltages in my case? Do I just connect 2V reference to Ref+ and call it a day or is it more complicated?