In Equation 14 on Rev D of the Datasheet, gives the value for the LP filter cap. Is there a practical limit, or is the part capable of driving humongous capacitance? If there is a limit, what is it?
There is no limit if you are willing to wait around forever for the cap to charge. In practice the cap should to set at a level that adequately reduces the residual ripple of rms computaion.
As you may know, loading an op-amp with a large capacitance can be dangerous becuase it can add to the phase shift of the signal feeding back to the inverting input. If there is enough phase shift, the circuit can oscillate. The size of the filter capacitor that is used for averaging in rms detectors such as AD8362, AD8363 and ADL5902, does not present any such danger. It does not reside inside a feedback loop so making the capacitance value very large will not create instability. It will of course slow down the response time of the circuit.
Thanks for that.
However, I wander what the practicle limit of this is, given the cap must be driven.
How large a capacitance is practical, and what frequency does that equate to?
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