Fixed 5V rail for low-current industrial loads
The STMicroelectronics LM2931AZ50 is a single-output positive LDO regulator delivering a fixed 5V output at up to 100mA. It is built for through-hole assembly in the TO-92-3 package, a footprint common in legacy industrial controls, sensor modules, and auxiliary bias supplies where board space is not the constraint. The 75dB PSRR at 120Hz makes this part a practical choice for cleaning up rectified line-frequency ripple on a 5V analog rail — think op-amp front-ends or ADC reference supplies where 120Hz hum would otherwise couple into the signal path. Dropout is rated 0.6V max at 100mA, so the input rail needs at least 5.6V to maintain regulation at full load. That headroom is typical for a 7.5V or 9V unregulated bus stepping down to a clean 5V.
Temperature range and protection set
The quiescent current sits at 1 mA typical, which keeps the thermal budget manageable in still-air TO-92-3 mounting. On-chip current limit and thermal shutdown are included — no external clamp diode needed for short-circuit protection on the output. The maximum supply input is 26V, giving ample margin for a 12V or 24V nominal rail.
Obsolete — sourcing through surplus channels
The LM2931AZ50 is listed as obsolete by STMicroelectronics. No direct replacement part number is published on the record. Date-code spread and packaging condition are confirmed at quote time; sealed factory tubes with consistent date codes are the preferred sourcing grade.