Why this LDO exists for automotive rails
The LM9036QMX-5.0/NOPB is a 5 V fixed-output linear regulator rated for 50 mA continuous output, built for the 12 V and 24 V automotive electrical system where the input can hit 40 V during load dump. The 60 dB PSRR at 120 Hz attenuates alternator ripple before it reaches the sensor or MCU supply rail. The 20 µA quiescent current keeps the regulator alive on the battery in key-off always-on domains.
Dropout and transient headroom
Maximum dropout is 0.40 V at 50 mA load — the regulator stays in regulation when the battery dips during cranking. The 40 V maximum input gives margin above the typical load-dump clamp used in many ECU front-ends. Protection features include over-temperature, reverse polarity, and short-circuit — the reverse-polarity block saves an external series diode on the input, which would otherwise add dropout voltage and quiescent current.
AEC-Q100 grade and production status
The AEC-Q100 qualification is listed in the series designation, which means the part has passed the automotive stress tests for temperature cycling, ESD, and latch-up. The ROHS3 compliance is confirmed.