Very difficult to say, the manufacturers use in house codes which often only appear in their data sheets, and it is possible that codes may be duplicated across different manufacturers. A search for LX4 yields some results, the XC9236 for one, a SMPS chip. Does that match up with the components around it on the PCB, an SMPS will normally have an inductor, and a few large value caps (upwards of a few uF often)
http://www.smdmark.com/en-US/smd-code-320.html lists a number of 320 parts. Again, you may have to figure out what the possible application is on the board, and measure a few voltages around it to figure out what it might be.
Best I can do,
cheers,
Richard
