3.0 V fixed LDO for noise-sensitive auxiliary rails
The LP2980AIM5-3.0 is a single-output, fixed 3.0 V LDO regulator from National Semiconductor, delivering up to 50 mA in a SOT-23-5 package. It is designed for powering low-current analog or digital rails where a clean, regulated 3.0 V supply is needed — think sensor bias, reference buffers, or MCU I/O supply in mixed-signal designs. Key parametrics include a PSRR of 63 dB at 1 kHz, a maximum dropout of 0.22 V at full load, and a quiescent current of 95 µA. The enable pin allows external on/off control, and built-in protection covers over-current, over-temperature, and short-circuit events.
NRND — plan a last-time buy or second source
Existing production BOMs can still be filled through independent distribution, but new designs should select a current-production LDO with the same 3.0 V fixed output and SOT-23-5 footprint.
The 0.22 V dropout at 50 mA means the input rail must stay above 3.22 V to maintain regulation — a 3.3 V rail with 100 mV ripple still leaves 20 mV headroom. Below that, the output tracks the input minus dropout, and PSRR collapses. For battery-powered designs, the 95 µA quiescent current is the standby floor; the enable pin can pull that to near zero when the load is off. PSRR of 63 dB at 1 kHz attenuates a 100 mVpp ripple on the input to about 70 µVpp on the output — adequate for 10-bit ADC references but marginal for 16-bit precision without additional post-filtering.