Why the 500 mA rating matters — and where this part lives
The LM2937ET-5.0 is a positive fixed-output LDO regulator from Texas Instruments that delivers 5 V at up to 500 mA. That 500 mA current rating is the number that decides whether this part powers your load without dropping out — if your circuit draws 480 mA peak, you have margin; if it hits 600 mA, you will see the output sag. The TO-220-3 through-hole package makes it a field-swappable part — no hot-air station needed, just a screwdriver and a heatsink.
The input can go up to 26 V, so it handles unregulated supplies like a rectified 24 VAC transformer without needing a pre-regulator. Dropout voltage is a maximum of 1 V at 50 mA load, which means you need at least 6 V on the input to keep the 5 V rail clean. The part includes over-temperature, reverse polarity, and short-circuit protection — that saves you from adding external clamp diodes or a crowbar circuit on the output.
That does not mean it is discontinued today, but it signals that TI will eventually phase it out. If you are building a new BOM, look for a pin-compatible alternative in the same family — the LM2937 series shares the same TO-220-3 footprint and fixed 5 V output.