PSRR and output current — the two numbers that decide the rail
The LM317LCPWRE4 is a 100 mA adjustable positive voltage regulator from Texas Instruments, part of the LM317 family. Its PSRR of 80 dB to 65 dB at 120 Hz means it attenuates 120 Hz ripple from a rectified AC input by a factor of 10,000 to 1,800 — this is the spec that makes it useful for cleaning up a noisy supply rail before feeding sensitive analog circuitry.
Input and output voltage envelope — where it fits in the power tree
Maximum input voltage is 38 V, and the output is adjustable from 1.2 V up to 32 V. The single regulator output is positive configuration only.
Protection features and quiescent current
Built-in protection against over-current, over-temperature, and short circuit — the regulator survives a sustained output short without damage. Quiescent current is 2.5 mA typical, which is the current drawn from the input regardless of load; at 100 mA output this is a 2.5 % overhead, acceptable for most fixed-load bias rails.
Package and temperature grade — board-fit check
Supplied in an 8-TSSOP surface-mount package (4.40 mm width, 0.173" pitch).