This board is designed for high power red laser diodes in battery powered hosts.
0 - 350mA
The normal connections are shown in red. (Normally the laser housing will be connected to power -ve via the tail-switch and the laser diode case pin is used to make the connection from the housing to the driver board.)
The current regulation is via the +ve power supply to the LD+ connection.
The driver board usually sits with the LD+ and LD- pins on one side of the board (left-image above) and the ‘not used’ pin connected to the LD- pad on the opposite side of the board for stability.