@Runaway Pancake, I think you meant "Should be able to work. Philips recommended...", but I find this comparison a bit confusing.
I think this topic needs some sort of closure. Or else I would have settled with my initial "investigation" :)
We concluded that [u]the sensor can output up to about 3.x mA/u. I think everyone agrees that [u]this leaves the most common optocouplers out of the question[/u], since they would require about 10~20mA to function reliably.
Moving forward. As I gather, an open collector output can either be open (high impedance) or closed (tied to the emitter which would be GND). Is this correct? So it stands to reason that any open collector needs to be provided with an arbitrary V+ through a resistor/load, just like a NPN BJT or N-channel FET does. Right?
Ok, so [u]using a NPN transistor[/u] in this case, it would invert the logic, and thus require a PNP transistor to restore the logic.
Now, [u]in the case of a comparator[/u], if its output is also open collector, then it requires a pullup, and it [u]would[/u] invert the logic; so the trick here (to NOT invert the logic) is connecting the 3.3v signal to the inverting input, and the voltage reference (1.7V) to the non-inverting input. Just to be complete and aware of the implications, [u]the circuit would draw about 10mA continuously while the output is LOW/u.
The amount of searching and reading required to reach this reasoning... Please tell me I'm right. But only if I am :)
If all is well, let's try to provide the forum with some answers: - One solution is using a comparator. A good choice for this purpose would be the LM393-N, plus two or three parts (resistor pair/diode(s) for the voltage reference, and the pullup resistor on the output). Concern: 20 circuits like this would draw about 5W. - If more output current is required (>15mA), and lower "idle current", the N-channel+P-channel FET pair would be best. Along with some resistors as well. In that case, the N-channel FET BS170 looks good for the job, however I can't find the adequate P-channel partner for it.
I'd like to verify these allegations with you guys if possible. Both solutions are desirable to pursue, for verification and energy efficiency comparison.