| ??? 02/18/09 14:44 Read: times |
#162547 - Don't confuse "OPamp" with "OPamp circuit"! Responding to: ???'s previous message |
Kai Klaas said:
Ap, you confuse the input voltage of OPamp with the input voltage of OPamp circuit!
Look at this scheme: 
....So, the differential input voltage of OPamp circuit is 20V - 15V = 5V. But the differential input voltage of OPamp is 3.7736V - 3.7736V = 0V! In reality you will notice a slight deviation from zero, caused by the specified offset voltage. So, the differential input voltage of OPamp is within safe limits. Also, the maximum common mode input voltage range of LMP2234 of -0.2V...4.2V isn't violated either, because the common mode input voltage is 3.7736V. The second amplifier amplifies the output voltage of first OPamp and fabricates an output voltage of 1.1628V x 4.3 = 5.000V. Et voilà! Kai Thanks Kai , yes I got confused between the circuit and the Opamp. I have a question ,thats when is the differential input maximum voltage gets violated as the opamp always tries to maintain similar voltages at its input terminals . I read a lot regarding its use in balanced line drivers audio etc . Regards/ Ap |
| Topic | Author | Date |
| Opamp question | 01/01/70 00:00 | |
| Please specify! | 01/01/70 00:00 | |
| Oops here its | 01/01/70 00:00 | |
| Mistake? | 01/01/70 00:00 | |
| transfer function | 01/01/70 00:00 | |
| Vout = V2 ? | 01/01/70 00:00 | |
| I 'm entirly confused... | 01/01/70 00:00 | |
| I explain it again | 01/01/70 00:00 | |
| So Vout = V2 - V1 | 01/01/70 00:00 | |
| I do have a common GND | 01/01/70 00:00 | |
| So Vout = V2 -15 ? | 01/01/70 00:00 | |
| trying to achieve | 01/01/70 00:00 | |
| Reference | 01/01/70 00:00 | |
| Reference | 01/01/70 00:00 | |
| Much clearer but.. | 01/01/70 00:00 | |
| Not clear | 01/01/70 00:00 | |
What VOut range do you want? | 01/01/70 00:00 | |
| I think this will do the trick... | 01/01/70 00:00 | |
| re: transfer function | 01/01/70 00:00 | |
| re: transfer function | 01/01/70 00:00 | |
| Ohm's law | 01/01/70 00:00 | |
| Oh the internal protection of opamp! | 01/01/70 00:00 | |
| Errr... | 01/01/70 00:00 | |
| Don't confuse "OPamp" with "OPamp circuit"! | 01/01/70 00:00 | |
| Don't confuse "OPamp" with "OPamp circuit"! | 01/01/70 00:00 | |
| If the feedback loop doesn't work... | 01/01/70 00:00 |