Pin-compatible regulator with high efficiency for fixed voltage [via]
For decades, the linear voltage regulator of the 78 series and its variants have been extremely popular, because these three-legged ICs allow stable supply voltages in the low voltage range to be created in a cost effective way. However if the difference between input and output voltage is considerable, efficiency decreases and the wasted heat must be dissipated which is not only costly and space consuming, but also a source of problems with thermal drift in sensitive and precision electronics. The use of switching regulators on the other hand generally requires more external parts and greater board surface. A modern replacement for the popular 3-pin voltage regulator would therefore make life easier for many electronic designers and engineers.
K78XX = switch-mode LM78XX – [Link]