300 mA LDO — dropout and PSRR define the rail budget
The LDK130PU30R is a fixed 3 V output linear regulator rated for 300 mA continuous. PSRR holds at 55 dB from 120 Hz through 10 kHz, which covers both rectified mains ripple and the fundamental switching frequency of most downstream DC-DC converters. That bandwidth matters when the LDO sits after a switcher to clean up the output for an analog rail.
Quiescent current and enable — always-on battery rail fit
Quiescent current is 60 µA typical, maxing at 120 µA. For a sensor node or microcontroller that spends most of its time in sleep, that draw sits below the self-discharge rate of a 100 mAh coin cell — the regulator isn't the dominant load in standby. The Enable pin lets the system power down the LDO entirely when the rail isn't needed, cutting the quiescent current to near zero. Over-current and over-temperature protection are built in, so a downstream short doesn't cascade upstream.
The 6-XFDFN package (1.2 x 1.3 mm footprint) is a tiny DFN with an exposed pad. Surface-mount only, no through-hole variant. The 6-DFN (1.2x1.3) supplier device package is the same mechanical outline as the 6-XFDFN — confirm the land pattern from the ST application note before committing the board layout.
ROHS3 compliant per the manufacturer's declaration.