Thin shrink small-outline packages, or TSSOPs are a type of surface mount IC package. They are notably very low-profile (about 1mm) and have tight lead spacing (as low as 0.5mm). They are frequently used for RAM or Flash memory ICs dues to their high pin count and small volume. However, they are being supplanted by ball grid array packages which can achieve even higher densities. - Wikipedia

     Thin Shrink Small Outline Package

TSSOP-20	TSSOP-24
TSSOP-28