Parts from with the SPX3819M5 base number from MaxLinear have a suffix system that isn’t explicitly described in the datasheet but does come up once in awhile when identifying parts.
The numbers are formatted as SPX3819xx-L-y-y/zz where:
xx = device package aka footprint
L = Internal, all orderable numbers include this suffix
y-y = Output Voltage (fixed)
/zz = Packing Type
For more information on this series see the following post from another of our techs:
MaxLinear SPX3819M5-L-3-3/TR part marking