# How to determine if given OpAmp model supports single supply (Ex. OPA167x)

Reading OpAmp datasheets I often struggle with the task of determining whether a given model of OpAmp can be used with single supply or not.

Sometimes, there is a plain statement in the features. But most of the time, it is not explicitly written. For example, in the OPA167x datasheet, the manufacturer only says

Wide supply range:– ±2.25V to ±18 V, or 4.5 V to 36 V

I guess thats enough information here, but are there any other cues (or words) that I can look for? Due to english not being my native language I might miss something.

• An opamp neither knows nor cares. Why should it? – Andy aka Feb 14 at 10:05
• @Andyaka: For some applications where power rails are noisy, an op amp with a ground reference pin may be able to offer better power supply rejection than one without, since common-mode compensation could be applied relative to a clean ground rather than to noisy power rails. – supercat Feb 15 at 19:19
• Maybe there can be an opamp with a ground reference pin? Never seen one. – Andy aka Feb 15 at 19:49

Two parameters affect whether an op amp can support single-supply, low-voltage operation -- minimum total supply voltage, and output voltage swing.

If output voltage max 12V with 15V supply (for example with a classic 741 op amp), then it needs 3V of "headroom". This is not a formal specification, but something that is inferred based on the specified output voltage limits at specified supply voltage test condition (VCC - VOHmin) and the (VSS - VOLmax).

Running a 741 from 5V single supply doesn't work because its output voltage is too constrained, max output voltage would be 2V but min output voltage would be 3V. This forces the output to sit near the center without any ability to drive signal.

Sometimes the output voltage swing is not symmetrical, it may be weaker driving high output and stronger on low output voltage; or there may be "crossover distortion" when it changes from being a current-source to a current-sink. Unfortunately datasheets don't usually call attention to this kind of distortion, except to specify it is guaranteed below some amount.

All OPAmps can be used with a single supply, but some are easier to use than others.

A key criterion for single supply use is that the input common mode voltage should include the negative supply, usually connected to ground.

A very useful criterion is that the output should drive to or nearly to the negative supply.

If you use an op-amp, it really just needs large enough supply voltage between the supply pins. So the op-amp does not care if you have 12V single supply or +/- 6V dual supply, from the op-amp point of view it just has supplies, it does not make a difference.

However, something else in your circuitry might require a certain configuration for the power supply, like ability to input and output negative DC voltages in respect to common ground.

Ground is a concept invented by humans so we can specify other voltages relative to it. Circuits don't care which node humans label as "ground." An op amp that can take a supply up to +12V can be run from +/-6V, and one specified for +/-15V can as easily be run from a single-ended 30V supply. Whether the spec sheet indicates single-ended or differential supplies is primarily a matter of marketing.

• You might also note that, unless otherwise specified, all input and output voltages must remain between the supply rails, whatever they happen to be. (I can see someone taking your original description and wondering why a 0-12V-supplied opamp won't play nice with a 0V-centered AC-coupled signal. Automotive audio, for example.) – AaronD Feb 14 at 18:45