I'm familiar with the configuration to make an LM317 (voltage regulator) into a current source. You connect a resistor between the Vout and Adj pins (Say 1.24 ohms) and draw the output directly from the adjust line (not the Vout line). With that resistance, you get a constant output current of about 1 amp. Easy peasy.
I'm trying to do that with an XRP29302. They are also linear regulators, but with some added bells and whistles. Instead of the 3 pins of the LM317 (Vin, Adj, Vout), it has 5 (Vin, Enable, Adj, Vout, Gnd). I tried hooking it up in a similar way, but it seems to be no go. (It works somewhat, but the output current is far too low.) I don't know what I am doing wrong. I think I have to incorporate the gnd in an appropriate way, but not sure how.
Some LM317 info is here: http://en.wikipedia.org/wiki/LM317
Some XRP29302 info can be found here: http://www.datasheetdir.com/XRP29302+LDO-Regulators