Firstly, thanks for the pointers on how to find the part markings for the TPS2051B.
However, I disagree with the comment about "No real need to have it in the datasheet".
1. In my case, I need the part markings to give to my incoming inspection department, in order that they might confirm that the distributor has sent us the correct device.
2. Many (most) vendors are including this information in their device datasheets, especially since the increased use of the smaller packages that often don't have enough space to put a "traditional" part marking.
3. If the manufacturer is forced to use a "code", (viz: PLJI in the case of the TPS2051B), then our I/C inspection need to know it.
4. Particularly in the case of this family of devices, since the "B" version has an active high ENABLE pin, while other members of this family use active low ENABLE.
(this is a functional difference, not "just" a performance parameter!)