Op-amp supply rails and common-mode voltage range considiration.

Status
Not open for further replies.
D

David_

Advanced Member level 2
Joined
Dec 6, 2013
Messages
573
Helped
8
Reputation
16
Reaction score
8
Trophy points
1,308
Location
Sweden
Visit site
Activity points
12,242
Hello.

I have a circuit with a op-amp amplifying a 0-3,3V signal into -3 to +30V signal, as well as another 0-3,3V signal into +3 to -30V.
First I thought to use a op-amp that could be supplied with +33V/-5V & +5V/-33V, or something very similar. But now I have selected a op-amp that could be supplied with ±30V, so that op-amp(LTC2057HV) could be used with almost equal supply rails. Just offset them slightly to ensure a max +30V output for one and a min -30V output for the other.

Is there anything to gain by using equal or almost equal rails as opposed to use +33V/-5V & +5V/-33V?


I have read a lot about input voltage common-mode range but there seams to be something I can't get my head around.
 

Although you have nothing to lose, you may find it slightly more difficult to split a, say 40V supply into +35 and -5. It will be relatively easier to split a 60V into +30 and -30. However an OP amp working with voltages as high as 60V should be expensive and the price may not be justified over the small difficulty of un-equal voltage splitting.
 

Actually the LTC2057HV cost about 5USD, which in my application is not much. The supplies comes from a center-tapped transformer so splitting supplies is not a problem, I will have a LM317s & LM337s or something equivalent so the voltage levels are easy to choose. In the current design I have pots to adjust the voltages but I will change those into resistors. Its all SMT parts.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…