I'm still relatively inexperienced with circuit design and I am wondering if I am misunderstanding something fundamental about this particular op amp. The AD8615 series is a single supply op amp, but one of the listed application is photodiode preamplification. In general, one wants to recieve a signal from 0V to some voltage as the readout for the photodiode. SInce the headroom of the lower rail is something on the order of 10s of millivolts, you would want the lower rail to be below ground so that the signal can reach all the way down to 0V. This is what is shown in the sample circuit diagram of included in the datasheet. Where the supply voltage is +/- 2.5 volts. Now, when I read the absolute ratings, the input voltage is listed as gnd to Vs. and the supply voltage is 6V. So it seems like you cannot run this on dual supply voltages. The specifications of the op amp and the listed application does not seem to match. Can someone explain that?