The data sheet shows that Vout cannot reach 0V even if Vin = 0V. The data sheet states that the minimum voltage swing from the rail is ~ 3mV. Do we have any information on this for large loads (1M or 5M)? Would there be much improvement? I did not see hardly any difference in Vout in a TINA simulation, but I wanted to check and see if we had any test information on 1M or 5M load.
Thanks for your help with this!
Richard Elmquist
Richard,
The output voltage swing to the rail is limited by the saturation voltage, Vsat, of the output transistor where the transitor acts like a resistor - see ohmic region (Ron) of Ids vs Vds transistor curves below. The closest swing to the rail occurs under unloaded condition and is limited to Vsat due to quiescent current, IQ, of the output stage - see red arrows below. For that reason decreasing load to 1M or 5M or infinity will make little to no difference in terms of how close the output may swing to its rail because under unloaded conditions, Iout=0, the swing is controlled by Vsat=~IQ*Ron.
