Quote:
Yes if the amplifier is used by an "electronic person" and the person has a lot of time to check the bias.
You still need a electornic dude to use the eqipment, needing to know excatly where to hook up the meter. (Hint all amps are diffrent)
So no, your not making life much easier for unexprienced people. And is likeley harder than just multimeter.
The refrence shifts the output by a dc bias(FIG 49), it dosen't limit the maximum voltage swing.
Sure you have some feedback from pins1 8 to set the gain, but there is no limit on maximum otuput voltage and is unacceptable design with regards to reliablity.
If any transient voltages on op amp turn on the micro will cook, even if the chip is designed to rise from 0V you cannot turst that it will do that every time.
The micro will burn feeding more than 5v into the pins.
Also good luck, you don't have any externally connected pull up or down resistors.
You can't rely the fact there may be internall pull up or low resistors.
Also you are not increacing the accuracy by using op amps, rather sense the voltage directly with the micro and then manipulate the data.
Also you have not shown the connection scheme for ADC voltage refrence, So I assume your using the micro 5v vcc voltqage as the refrence which is standard, So minimum ADC resolutiuon is 5/256 = 0.0195V which is quite large (19.5mV)
19.5mV of voltage error is unacceptable for a system like this.
You've also indirectly implied the voltage your sensing as is 90mV, so you will have massive error sensing something that is 0 to 300mV inputted to the micro.
Also good luck with keeping out noise using the 1Meg and 1Meg resistor divider to input the voltage into micro.