tt119 is a non-isolated AC 220v to 5v fixed output of a step-down chip, like the triode package sot23-3, very small, 5v peak current in 200MA, it is recommended to use within 150MA.
In 12V to 5V applications, most of the requirements will be high output current, voltage regulator LDO can not meet, need to use DC-DC buck chip to continuously regulate 5V, output current 1000MA, 2000MA, 3000MA, 5000MA, etc. Different output currents can choose the appropriate buck chip to use.