Looking at the datasheet http://www.ti.com/lit/ds/symlink/lp38691.pdf page 2 it shows a connection diagram for LP38691DT
And looking at the recommed design for it http://www.ti.com/lit/ml/mmsf021/mmsf021.pdf shows:
identifying the pin number as 1,2 and 3.
Can I assum that:
1 - Vout
2 - GND
3 - VIN