I have a bi-directional current sense opamp (INA214), where I'd like to alternate the VREF between GND and 10V. Page 22 ("9.2.2 Bidirectional Operation") in the datasheet has more information.
I also have a TL431 which I'd like to use to provide a stable 10V reference.
What would be the best way to make a circuit, that receives a 0V/5V signal, to provide a reference voltage that is stable enough to act as a voltage reference? Ideally the circuit would have low power consumption when the output reference is GND.
Option 1: NPN on opamp signal
Maybe something like this? I'm not sure about the highest value possible for R1 (to reduce power consumption), and the other resistors as well.
simulate this circuit – Schematic created using CircuitLab
Option 2: Multiplexer
Perhaps using a CD4052B multiplexer?
Best Answer
What you're looking for is called an analog multiplexer. The most common example is probably the classic CD4066. In general, multiplexers work as a group of FETs tied together at one end. For a 2-input mux, it would look something like
simulate this circuit – Schematic created using CircuitLab
A select line turns on one FET while turning off the other. Your original concept was OK in principle, but the saturation voltage of the transistor would have meant that the zero output would not be exactly zero.
Also note that this is a simplified circuit - a real multiplexer will use multiple FETs to allow a full range of inputs. See the 4066 data sheet for more details of how it's actually done.