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Why would an oscilloscope probe ever draw more than a few mW or even microwatts?

I'd expect a normal optoisolator module to work for a probe like that. No need for 180mA+ transferred between circuits.

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An oscillator probe is an example where electrical isolation + signal (aka: communications) are useful. But under no circumstances should 500mW of power be sent through such a setup in either direction.

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The amplifiers in high-speed active probes can use nontrivial amounts of power. I don't have specific numbers as the probe/scope interfaces are proprietary, but I wouldn't be surprised if some of the wired (non-isolated) probes draw multiple watts.

> I'd expect a normal optoisolator module to work for a probe like that.

Absolutely not. "Standard" optoisolators tend to be slow and have analog characteristics which are unsuitable for an oscilloscope.

Active probes can draw several watts. Probably shouldn’t, but no one is optimizing them for efficiency

IIRC, leaker and worse-power BJTs handle higher-power and have lower noise. (Though Google says JFETs have even lower noise).

But the numbers discussed here is a lot more power than I was expecting. I'm guessing that at the GHz-range, everything uses more power though.

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