taken from the web (as usual):
LED Drivers: are current control devices that replace the need for resistors. LED Drivers respond to the changing input voltage while maintaining a constant amount of current (output power) to the LED as its electrical properties change with temperature.
And, that's why they are rated with varying voltage and a single current rating. The point is not to argue about the definition of constant current, or whether or not a particular device fits one's definition completely, the point is they are incredibly small, cheap and available. After I get done with some testing, they may represent a really cheap and small method of powering small smart devices from wall power without a wall wart and a bunch of circuitry that takes up space.
And, Lefty, that was a heck of a find. NIce job. I love using those little things to battery power devices. My problem has always been that I have exactly zero skill at making low power devices. I can measure and control 440V three phase welders with the best of them, but I can't make a darn battery last over night......sigh.