5V fixed rail with 49dB PSRR at line frequency
The STMicroelectronics L78L05ABUTR is a fixed 5V positive-output linear regulator delivering up to 100 mA in the SOT-89-3 package. Its 49 dB PSRR at 120 Hz means the output ripple from a full-wave-rectified mains supply is attenuated by a factor of ~280 — critical when powering analog front-ends or MCU ADCs from an unregulated DC bus.
Input range, quiescent draw, and protection
Maximum input voltage is 30 V, giving 25 V of drop-out headroom above the 5 V rail — the part dissipates the difference as heat, so the 100 mA output at high input-to-output differential demands attention to the SOT-89-3's thermal pad. Quiescent current is 5.5 mA typical, with a 6 mA supply maximum; this Iq floor matters in always-on or battery-backed 5 V rails where every milliamp counts. Built-in protection covers over-current, over-temperature, and short-circuit events — the regulator survives a sustained output short without damage, though the thermal-shutdown cycle will pulse the rail.
Package footprint and mounting
Housed in a TO-243AA (SOT-89-3) surface-mount package, the L78L05ABUTR occupies a compact board footprint suited to space-constrained PSU sections.
It is RoHS3 compliant, meeting the current EU restriction directive for lead and other hazardous substances.