I did check one NUD4001, one set resistor 2 Ohms and one LED. It gives right current about 0.350 A. Soon as I do 2 parallel NUD4001 in order to get double current, I actually get 1/4 of current. I did follow data sheet instructions, I did make paraller circuti with LM 317 and it worked nice, double the current from one chip. It jsut doesn't work with NUD4001. I put 7 leds, 27V (3x9V battery), used 2 chips, 2 resistors 2 Ohm each and got .350A, not 0.7A.