I'm trying to make the voltage reference for an INA214 opamp selectable between GND, 4.5V and 10V. I'm using a CD4051B multiplexer.
However, the 10V VREF gets pulled down to 5.84V, and I can't figure out why.
- INH, Vee, Vss to GND
- C to GND
- A, B to 5V (thus selecting CH3 as output)
- CH3 to GND
- CH1 to D1 output
- CH2 to D2 output
- Output measured by multimeter
- 4.95V when D2 is connected to any pin on the mux
- 0V when D2 is not connected
- 4.54V when B is GND, no matter if A is 5V or GND (D2 is not connected)
which is strange, because CH1 is A=1 B=0.
What is going here? Are the TL431s interfering with the function of the CD4051B, or...?
By the way, am I required to connect the other pins/channels to ground, or can they be floating?