PSRR envelope and what it means for your rail
The LDBL20D-18R delivers 80 dB of power-supply rejection at 1 kHz, rolling off to 55 dB at 100 kHz — that 25 dB drop across two decades tells you the internal error amplifier's gain-bandwidth limit. For a 1.8 V rail feeding a sensitive analog front-end, the 80 dB floor at audio frequencies means a 10 mV ripple on the input gets attenuated to about 1 µV at the output; above 100 kHz the rejection drops enough that a switching regulator's ripple needs a post-filter if the load is a high-resolution ADC.
Output current and voltage ceiling
Fixed 1.8 V output at 200 mA continuous — this is the rail budget for a low-power MCU core or a sensor supply that draws under 150 mA steady-state with headroom for startup transients.
Temperature grade and package footprint
The 4-STSTAMP package measures 0.47 x 0.47 mm, making it one of the smallest LDO footprints available; the 4-XFQFN body demands a tight PCB land pattern and a stencil aperture sized for the exposed pad's thermal relief.
Protection and control features
Built-in over-current, over-temperature, and soft-start protection — the soft-start limits inrush into a capacitive load, which matters when the downstream device has a large decoupling cap bank. The Enable pin lets a system sequencer or a GPIO hold the rail off until the upstream supply is stable.