Why the TO-3 package matters for this 1.5 A regulator
The LM317H is the through-hole, metal-can variant of the classic adjustable positive regulator, rated for 1.5 A continuous output. The TO-3 package — a steel base with a nickel-plated can — conducts heat directly to a chassis or heatsink through the mounting flange, which is the main thermal path.
Ripple rejection and output range
PSRR is 80 dB at 120 Hz, dropping to 65 dB at the same frequency — that 80 dB figure means the output ripple from a full-wave rectified supply is attenuated by a factor of 10,000. For a 1 V p-p ripple on the input, the output sees roughly 100 µV p-p. The adjustable output range spans 1.25 V to 37 V, set by two external resistors. Maximum input is 40 V, so the dropout margin between input and output must be at least 3 V at full load.
Active production, TO-3 availability
The TO-3 package is — no tape-and-reel, so plan for manual or tube-fed placement.