Other Parts Discussed in Thread: ADS131E04
Hello:
I assume the control voltage of the part must not exceed the positive supply, though that is not crystal clear in the data sheet. In fact, the data sheet implies that is not necessary on the first page when it claims "3.3V and 5V compatible digital control inputs". I also note the minimum split supply called out as +/-2.7V.
The system I need to design this part into uses +/-2.5V for the TI ADS131E04 ADC, and also has available 3.3V for control signals.
It would seem I have two options here:
1. Run this analog switch at +/-2.5V, which is a little out of spec, and divide down the 3.3V logic to be 0 to 2.5V for control purposes (If that front page data sheet claim is misleading). Would the part be expected to reliably function as a switch under these slightly reduced voltage conditions? It is a low impedance switch, and if its typical 5 Ohms is moderately higher impedance under these +/-2.5V conditions that would be fine.
2. Run the part with unbalanced supplies, specifically +3.3V and -2.5V. This avoids any level translation on voltage control, and maintains higher total voltage on the part than the apparently desired minimum of 5.4V. I see nothing in the data sheet that would suggest this would not work, other than that the negative supply is not <-2.7V. Would there be any problem with this?
Thanks,
Farron Dacus