ON /OFF -- Allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total inputsupply current to approximately 80 µA. Pulling this pin belowa threshold voltage of approximately 1.3V turns the regulatoron, and pulling this pin above 1.3V (up to a maximum of 25V)shuts the regulator down. If this shutdown feature is notneeded, the ON /OFF pin can be wired to the ground pin orit can be left open, in either case the regulator will be in theON condition.
Damn. There's a million of those modules out there and they all seem based on a single design which doesn't provide access to the enable pin!Also, what the hell is with being able to buy 50 of these things for less than $2 each, but the chip all by itself would cost me $3.30 from Digikey at qty 250? Even if I bought TEN THOUSAND OF THEM, it would still be more than the fully assembled board!