100 mA adjustable regulator in an 8-TSSOP — bench-fit for low-power rails
The Texas Instruments LM317LIPWR is a 100 mA adjustable positive voltage regulator in an 8-TSSOP package. It takes an input up to 38 V and delivers an adjustable output from 1.2 V up to 32 V, set by two external resistors. This is the low-current, surface-mount variant of the classic LM317 three-terminal regulator, built for designs that need a clean, adjustable rail without the thermal mass or board area of the TO-220 version.
PSRR 80 dB at 120 Hz — what that means for a sensitive analog rail
Power-supply rejection ratio is listed at 80 dB to 65 dB at 120 Hz. That 80 dB figure at line frequency means the regulator attenuates 120 Hz ripple from a full-wave rectifier by a factor of 10,000 — a 1 Vpp ripple on the input becomes roughly 100 µVpp on the output. For an op-amp or ADC supply rail, that keeps the ripple floor below the noise floor of most 12-bit systems. The 65 dB at higher frequencies still gives a 1,800× reduction, which is respectable for a 100 mA part in this package.
Industrial temperature range and protection features
On-chip protection includes over-current limiting, thermal shutdown, and short-circuit current foldback — the regulator survives a hard output short without damage. Quiescent current is 2.5 mA typical, which matters for always-on or battery-backed rails where every milliamp counts.