I am looking into measuring both positive and negative voltages using ADC. My input voltage is in range from -55 to +55V, which is total of 110V. ADC I am using is MCP3424, since it is relatively easy to pair it with Raspberry Pi. MCP3423 is differential ADC with positive and negative inputs for each port. I am looking to connect negative(-) port to gnd, so I feed the voltage to the positive input. It gives me range from 0 to 2.048V. (readings of ADC are 18-bit)
I am looking to convert -55V to +55V range into 0 - 2.048V range. With some googling and my limited electronics knowledge I came into the following circuit:
- would this work fine?
- to which voltages I should connect op-amp voltage rails? OA1 to +5 and gnd, and OP2 to +55V and -55V? In that case, I would need high voltage op-amp, for example LTC6090?
- do I need protection diodes at input or at output?
Are there any other issues I am not seeing?