ZHCSJO8 May 2019 OPA818
ADVANCE INFORMATION for pre-production products; subject to change without notice.
In typical split-supply operation, the mid-point between the power rails is ground. Mid-point at ground in split-supply configuration is a valid operating condition for OPA818 when symmetric supply voltages that are greater than or equal to ±4 V are used. This facilitates interfacing the OPA818 with common lab equipment such as signal generators, network analyzers, oscilloscopes, and spectrum analyzers most of which have inputs and outputs referenced to ground. However, when split-supply voltages less than ±4 V are used, care must be taken that the input common-mode range is not violated because the typical input common-mode range of OPA818 includes VS– and extends up to 3.2 V from VS+. For example, when ±3 V supplies are used, the input common-mode of the signal must be typically 3.2 V from VS+ and 3.6 V from VS+ under maximum specified input common-mode range. This means ground is not included in the input common-mode range with ±3 V supplies resulting in erroneous operation if the input signal has ground as the mid-point. To prevent this situation, +4/–2 V supplies can be used.