Fixed 1.8 V rail with 65 dB PSRR — what that means for your supply
The MAX8891EXK18+T is a fixed-output positive linear regulator from Analog Devices, delivering a regulated 1.8 V at up to 150 mA from a maximum input of 6 V. The headline spec is the 65 dB power-supply rejection ratio at 10 kHz — that is enough attenuation to keep switching-regulator ripple off a sensitive analog or RF rail without adding a second-stage filter. Quiescent current sits at 40 µA, so the part is viable for always-on or battery-powered nodes where every microamp counts. The enable pin lets you gate the output for sequenced power-up or sleep modes.
Package and thermal — SC-70-5 footprint
Housed in a 5-lead SC-70-5 (SOT-353) package, this LDO fits into tight layouts — think sensor modules, handheld instruments, or compact IoT edge nodes. Surface-mount only; the small footprint means the thermal budget is limited, so 150 mA continuous at high ambient may need derating. The -40°C to 85°C operating range covers industrial and outdoor telecom enclosures.