We are using the LMH6611 OpAmp from TI as it offers high current rail-to-rail output (100mA) and high frequency (345MHz), which seems to be quite unique in this combination. In addition, the power consumption is only 3-4mA due to the datasheet, which is also important for us.
However, we noticed that our opAmps draw more than 30mA, even if they do not have to drive anything.
The setup is a multilayer PCB with GND and 3.3V plane with decoupling capacitors near the chip. the opamp is powered by this voltages.
A 1:1 voltage divider passes half the supply voltage to one input, the other usually gets an external signal, but for testing, we connect it to GND or the supply voltage. The output is not connected to anything for the test.
We also inspected supply voltage, inputs and output via scope, but we found no increased noise, oscillation or whatever. We tested several chips, even from different batches, always with the same result. We have no idea any more and start to believe in an error in the datasheet...
Does anyone have an idea why this opAmp draws so much more current than written in the datasheet?
Here is an schematic.
The current was first observed on the bench power supply, later we measured it directly at the supply pin of the opAmp either via ampere-meter or voltage drop across a measurement resistor.
simulate this circuit – Schematic created using CircuitLab