The "Planck units" are generally the smallest units used - except for the Planck unit for mass, which is fairly large.

Planck didn't have an element named after him, but he has a fundamental physical constant named after him, the Planck constant. And, because it is a fundamental physical constant, it has "spawned" a "group" of units (called Planck units) that are interrelated because they all contain the Planck constant. The Max Planck Institute for Developmental Biology and the Max Planck Institute of Biological Cybernetics on the Max Planck Campus are named after him. The Max Planck Society (Max-Planck-Gesellschaft) operates some 80 research institutes all over Germany, (and a few in other European countries), which usually bear the name "Max Planck Institute (MPI) of ...". The Society does basic research in the natural sciences, but also does work in the social sciences and humanities. Links are provided.

You can find the dimensions of derived units in the Wikipedia article on "Planck units".

The two main systems are the International System of Units (SI units) and the Planck units. The latter are often more convenient in the study of quantum physics.