I need to buffer a single sided signal feeding an ADC and would like to use a single sided op-amp at the same voltage of the ADC to protect it from over/under-voltage.
I need to be able to read the signal right down to 0V (upper rail not so important), and I'm afraid a rail to rail op-amp won't cut it as they usually can only get down to 20-50mV off ground.
One thing I was thinking was putting a diode on the output of the op-amp with a weak pull-down resistor and connecting the feedback after the diode to keep the op-amp output around 0.6V off ground to get 0V on the input of the ADC.
Another solution would be to use a difference circuit and subtract the input from a reference voltage so that zero on the input would be somewhere easily within the output range of the op-amp. My worry with this is that the input signal (which is coming from the outside world) won't see ground. It will be a floating voltage and I'm not sure I should assume outside signals will be able to work with that.
Any other suggestions that don't involve using a two rail op-amp?
Any help greatly appreciated!
I need to be able to read the signal right down to 0V (upper rail not so important), and I'm afraid a rail to rail op-amp won't cut it as they usually can only get down to 20-50mV off ground.
One thing I was thinking was putting a diode on the output of the op-amp with a weak pull-down resistor and connecting the feedback after the diode to keep the op-amp output around 0.6V off ground to get 0V on the input of the ADC.
Another solution would be to use a difference circuit and subtract the input from a reference voltage so that zero on the input would be somewhere easily within the output range of the op-amp. My worry with this is that the input signal (which is coming from the outside world) won't see ground. It will be a floating voltage and I'm not sure I should assume outside signals will be able to work with that.
Any other suggestions that don't involve using a two rail op-amp?
Any help greatly appreciated!