AD8674: Supply Voltage

Document created by analog-archivist Employee on Feb 23, 2016
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To the 8 inputs of an AD7938 ADC we would like to use the AD8674 quad opamp.
The opamp output signals to be acquired go from 0V to +2.5V. We would like to
power the opamps from -2 to +5V. We have tried it and at a first glance they
seem to work. In the specs, however, it says that one should power them with a
voltage between 8 to 36V. Is there a risk if we power them from -2 to +5V? If
yes, which?
Many thanks in advance for your comments!


Op amps in general can be used from any supply voltages (symmetrical or
asymmetrical) that are less than the total maximum power supply from V+ to V-.
The only thing to be careful of is that the inputs and outputs have headroom
limitations and cannot swing all the way to the supply rails.
You will see from the specifications for +/-5V operation, input voltage range
is +/-2.5V. That is there is 2.5V headroom to each supply. The absolute maximum
rating for the power supplies is +/-18V, which is 36V between –Vs and +Vs. The
minimum rating is 8V between –Vs and +Vs.