The voltage between the adj and output pin is held constant with a very low current flowing through the adj pin. This the current through the resistor between the output and ground is constant allowing the output voltage to be easily changed by altering the resistor between adj and gnd.
So, when operating normally, there is a known voltage between adj and output, but I've never seen it used separately as a reference.
Actually with t this kind of regulator (LDO) the output at the Adj.pin is related to Gnd ,not to the output.
see #10 and #16 above.
Is using this voltage for other purposes possible?
Yes, if you don't load it. i.e (connect it to a high resistance "input",or use a high resistance buffer).
This will be a non traditional thing to do,for the purpose of saving some pennies,not using another voltage reference.
That said,it is against the KISS rule...
Will this work for the o.p here?
No,it will not!
Reason being he wants to activate the Shutdown pin of the same LT1763.
When in shutdown mode there is no output voltage at the output of the regulator,and the voltage at the Adj pin will go to 0v.
Using Vref at the Adj pin of the same IC to activate the Shutdown would cause unwanted behavior : either latch-up in the shutdown state or an oscillatory state on-off-on-off...
Xenobius,
the way to go would be to use a comparaor with a voltage reference like in #17,
the TLV3011-2.
BTW,
What is the intended voltage at the output of the LT1763 ?