This is supposed to be a discussion with the purpose of forcing issues relevant to the subject of the thread, specifically, Chico's inability to make this laser module work. Stamping your feet and shouting that you're right isn't helpful, nor is it necessary ... and it's not even true.

You said that LED driver, ST2221A, operates from 3 volts to 28 volts, and I can't verify that from the datasheets I can find. Further the thing's apparently no longer manufactured, at least accoring to the folks who sell 'em. Additionally, the datasheet
http://www.estopto.net/data/st2221a.pdf
seems clearly to show that the ST2221A uses a resistor from the positive [edit ... should have been negative] supply to set the current. You say it's a cookbook device. Well, show us one that doesn't require a well regulated constant voltage in order to provide a well-controlled constant current. That'll educate everyone who doesn't know, including, perhaps, the O/P.

Isn't that what a "discussion" of this sort is supposed to do?

RE