3 A fixed 12 V buck — 52 kHz switching sets the inductor choice
The LM2576S-12/NOPB is a 3 A step-down (buck) regulator from Texas Instruments' SIMPLE SWITCHER® series, delivering a fixed 12 V output from an input rail spanning 4 V to 40 V. The 52 kHz switching frequency is low enough that the external inductor and output capacitor are physically larger than in a modern 500 kHz design, but the trade-off is lower switching losses and a simpler layout that tolerates more parasitic inductance in the power path. Because it uses a non-synchronous rectifier (an external Schottky diode is required), the BOM includes one additional diode compared to a synchronous buck, but the part itself costs less and the diode's forward drop is predictable across temperature.
Package and thermal management — DDPAK with exposed tab
The TO-263-5 (DDPAK) package has five leads plus an exposed metal tab on the bottom.