Fixed 3.3 V output, 3 A buck — the SIMPLE SWITCHER® workhorse
The Texas Instruments LM2576SX-3.3 is a fixed-output step-down buck regulator from the SIMPLE SWITCHER® series. It delivers a regulated 3.3 V at up to 3 A from an input rail spanning 4 V to 40 V, switching at 52 kHz. The part is designed for point-of-load regulation in industrial, automotive, and telecom power supplies where a simple, robust converter is needed without complex loop compensation.
The 52 kHz switching frequency is on the low side by modern standards. It keeps switching losses low, which helps with thermal management in the TO-263-5 package, but it calls for a larger inductor and output capacitor compared to a 200 kHz+ regulator. For a 3 A rail, expect an inductor in the 33 µH to 100 µH range and a bulk capacitor sized for the ripple current. The trade-off is a simpler layout and better noise margin on the output. The 3 A output current is continuous, with the internal switch rated for that load across the full 4 V to 40 V input window. No synchronous rectifier means the freewheeling diode carries the full output current during the off-time — a 3 A Schottky diode (e.g., 1N5822 or equivalent) is the standard companion part.
Temperature range and package for industrial environments
The 5-lead footprint (one tab is the switch node) is standard across the LM2576 family, so a layout designed for the through-hole TO-220 version will not map directly.