Ripple rejection that justifies the linear regulator choice
The LM317K STEEL/NOPB is Texas Instruments' adjustable positive voltage regulator in the through-hole TO-204AA (TO-3) steel package. Its headline spec is the PSRR of 80 dB to 65 dB at 120 Hz — that's the ripple rejection a designer picks a linear regulator for over a noisy switcher, and it holds across the full 1.25 V to 37 V output range.
1.5 A output in a package that needs a heatsink
Rated for 1.5 A continuous output with a 37 V max input, this is a power part that demands thermal management. The TO-3 steel case is the classic two-screw flange-mount package — it bolts to a chassis or dedicated heatsink, and the tab is the output terminal. The 10 mA quiescent current is typical for a three-terminal regulator of this generation; the thermal budget is dominated by the (Vin - Vout) × Iout drop, not the Iq.
Protection and temperature range for bench and industrial gear
Built-in overcurrent, overtemperature, and short-circuit protection make this a rugged choice for benchtop supplies, industrial control boards, and legacy equipment repair.
Listed as active with a current lifecycle stage. This part is still in regular production, which means the buyer is not chasing last-time-buy lots or surplus date-code stock. The STEEL/NOPB suffix confirms the steel TO-3 package and lead-free (NOPB) finish — the standard RoHS-compliant variant.