Level shifting 8 output IO Expander from 0V-5V to -2.3V to +2.3V

analogdigital-logiclevel-shiftinglevel-translation

I have a circuit problem that I'm trying to find a solution for.

I have an 8 output IO expander which outputs 0V-5V. It is running analog switches which have a Vdd and Vss of +-2.3V.

Using the 5V right now is causing a dc offset and noise on the output of the analog switch.

I know I could just use an op amp to translate the voltage level, but that would require a lot of hardware for all 8 outputs.

I can't seem to find a level shifting IC that will accept a 5V signal and output a differential analog signal.

I've also thought about running it off of an 8 channel DAC. But that would be a costly solution.

Update for clarity:
I am looking for a single IC that can accomplish the level shifting for all 8 signals instead of having to use a group of discrete components for each signal.
OR, I am looking for an 8 ouput IO expander that has seperate supplies for communication with the microcontroller and IO outputs.

Best Answer

See below. When the input is at 0V, Q1 is on, the output voltage is pulled up to +2.3V. When the input is at 5V, the output is at -2.3V. Note the logic reversal.

You can use dual transistors etc.- they're not critical.

schematic

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