LM317MDT-TR

LM317MDT-TR is an STMicroelectronics LM317M adjustable positive linear regulator in DPAK (TO-252), tape and reel — the 0.5 A M-grade of the classic LM317 for bench supplies, industrial rails and battery-backed equipment. The grade is the selection point and the common ordering mistake: this code is the 0.5 A version, not the 1.5 A standard LM317 sold under other makers' codes on this site, so a BOM that simply says LM317 is under-specified. Output is adjustable from 1.2 to 37 V with the reference held at 1.2 V minimum, 1.25 V typical and 1.3 V maximum — those limits hold for VI − VO = 3 to 40 V, IO = 10 to 500 mA, TJ = 0 to 125 °C and dissipation within 7.5 W — set by two external resistors, with internal current limiting and thermal protection. ST's own Quality & Reliability table lists this exact code as Active (DPAK, Industrial grade, Ecopack2). Selection advice: dissipation is (VIN − VOUT) × IOUT and must stay within the 7.5 W ceiling with the DPAK's board copper as the heatsink — compute it for your rail and ambient, and step up to a 1.5 A code in a larger package when the product runs hot. Parameters verified against the ST datasheet and product page.