The gain for a regular noninverting opamp configuration is [ 1 + ( Rf / Ri )] .
This means that the output voltage will always be greater than or equal to the input voltage. But can we have a noninverting opamp configuration in which the gain is between zero and unity i.e. output voltage is lesser than the input voltage.
If figures will help, use the following ones:
An input voltage of +12 V. Desired output voltage of +6 V (half of input voltage). Positive and negative supply voltages provided to the opamp are +15 V and 0 V / ground.
No, you can't use the normal non-inverting configuration like that.
What you can do is use a voltage follower preceded by an attenuator.
If the input impedance of a resistive attenuator is too low, then use two voltage followers. One to which you connect your input voltage, then the attenuator and then another follower.