The LM2596T-12/LF03 is a fixed 12V output buck regulator from the SIMPLE SWITCHER® family, delivering 3A continuous from a 4.5V to 40V input rail. The 150 kHz switching frequency keeps EMI manageable but demands a larger inductor (typically 33 µH to 47 µH) and output capacitor than a 500 kHz+ part — factor the extra PCB area and component height into the layout. The non-synchronous topology means an external Schottky catch diode is required; the diode's forward voltage and thermal rating must be sized for the full 3A load.
Through-hole TO-220-5 — footprint and thermal path
The TO-220-5 formed-leads package has a metal tab that carries the ground potential and provides the primary thermal path. The 5-lead layout is not pin-compatible with the common 3-lead TO-220 — verify the PCB footprint against the supplier device package drawing before committing the board.