10V fixed rail, 1.5A — the selection mistake this LDO avoids
The ST L4940D2T10-TR is a fixed 10V positive LDO regulator delivering up to 1.5A from a maximum 17V input. Its 0.9V dropout at full load leaves headroom for a 10V rail even when the input sags to 10.9V — common in post-regulated 12V supplies for automotive or industrial control boards.
Dropout and thermal — sizing the copper pour
The D2PAK (TO-263-3) package with exposed tab sinks heat through the PCB copper pour. At 1.5A and 3V input-to-output differential, dissipation is 4.5W — the tab must be soldered to a 1oz copper area of at least 600mm² to keep junction below 150°C in a 70°C ambient. Quiescent current is 8mA typical, rising to 50mA max under heavy load — not a low-Iq part, so not the choice for always-on battery circuits, but acceptable for a continuously powered rail in a motor drive or an ECU.
The L4940 family shares the same pinout across fixed-voltage variants, so a 10V fixed output is specific.