As far as I know, a rail-to-rail op-amp is capable of providing output up to the power supply rails (i.e. from +VDD to -VDD.)
I've been using a TLC2272 op-amp to understand this concept.
According to the datasheet, the maximum allowable input voltage is VDD - 1.5 V. My input is 0-5 V, but the output is not showing the expected result. The peak has been clipped just like any ordinary op-amp. A zero-volt output is obtained for zero-volt input.
Check the schematic. I've built and tested the circuit practically, so ignore the simulation result.
The output voltage for various inputs is shown in the table below.
As expected, the output reaches zero volt for zero-volt input (ignoring 2.2 mV as it is a very negligible value.) For 5 V input, the output was supposed to be 10 V, but it is only 8.61 V. The input voltage is below the maximum allowed input voltage.
|1||0 V||2.2 mV|
|2||1 V||1.98 V|
|3||2 V||3.98 V|
|4||3 V||5.95 V|
|5||4 V||7.93 V|
|6||5 V||8.61 V|
Can anyone explain to me under which conditions I'll get rail-to-rail output?
Is my understanding of the rail-to-rail concept wrong?