cntrl.freak
New Member
School project: I am using a National LMC660 op-amp as a unity gain
high-impedance front-end to a TLC2543 adc. I intend for the sensor
input to the op-amp/adc is to be user selectable for either 0-5VDC or
1-5VDC. In testing, everything works fine until I disconnect the
sensor input from the op-amp. With the input to the op-amp open, the
output floats around 2 - 2.5 volts. I want the output of the op amp
to stay at the minimum value (0 or 1VDC), depending on range
selected).
Thanks in advance for any help you can give me!
high-impedance front-end to a TLC2543 adc. I intend for the sensor
input to the op-amp/adc is to be user selectable for either 0-5VDC or
1-5VDC. In testing, everything works fine until I disconnect the
sensor input from the op-amp. With the input to the op-amp open, the
output floats around 2 - 2.5 volts. I want the output of the op amp
to stay at the minimum value (0 or 1VDC), depending on range
selected).
Thanks in advance for any help you can give me!