The OPA836 and OPA2836 devices are rail-to-rail output (RRO) operational amplifiers. Rail-to-rail output typically means the output voltage swings within a couple hundred millivolts of the supply rails. There are different ways to specify this: one is with the output still in linear operation and another is with the output saturated. Saturated output voltages are closer to the power supply rails than linear outputs, but the signal is not a linear representation of the input. Linear output is a better representation of how well a device performs when used as a linear amplifier. Saturation and linear operation limits are affected by the output current, where higher currents lead to more loss in the output transistors.

Figure 7-11 and Figure 7-37 show saturated voltage-swing limits versus output load resistance and Figure 7-12 and Figure 7-38 show the output saturation voltage versus load current. Given a light load, the output voltage limits have nearly constant headroom to the power rails and track the power supply voltages. For example, with a 2-kΩ load and single 5-V supply, the linear output voltage ranges from 0.15 V to 4.8 V, and ranges from 0.15 V to 2.5 V for a 2.7-V supply. The delta from each power supply rail is the same in either case: 0.15 V and 0.2 V.

With devices like the OPA836 and OPA2836, where the input range is lower than the output range, typically the input will limit the available signal swing only in noninverting gain of 1. Signal swing in noninverting configurations in gains > +1 and inverting configurations in any gain is typically limited by the output voltage limits of the operational amplifier.