Adjustable 1.2 V to 37 V rail — 500 mA ceiling in DPAK
The LM317MDT-TR is an adjustable positive voltage regulator from STMicroelectronics, delivering up to 500 mA output with an input range up to 40 V and an adjustable output from 1.2 V up to 37 V.
PSRR 80 dB down to 65 dB — ripple rejection across the audio band
PSRR is specified at 80 dB typical at 120 Hz, dropping to 65 dB at higher frequencies. The 10 mA quiescent current is typical for a three-terminal adjustable regulator of this era.
Active status — no obsolescence watch
The DPAK package variant is used in industrial and appliance power supplies. For BOM planning, the base number LM317 has multiple package derivatives — the DPAK version is the surface-mount workhorse for moderate current.
Over-current, over-temperature, short-circuit protection — built-in
The regulator includes over-current, over-temperature, and short-circuit protection. These are fold-back type — the output current reduces when the junction exceeds the thermal limit, then recovers when it cools. In a fault condition the part survives indefinitely, but the load sees repeated on-off cycles.