Automotive LDO for 1.8V rails — AEC-Q100 qualified
Texas Instruments LP5907QMFX-1.8Q1 is a fixed-output 1.8V LDO rated for 250mA continuous, in the SOT-23-5 package. Belongs to the Automotive, AEC-Q100 series — qualified to Grade 1 with a -40°C to 125°C operating range, meaning it can sit on an engine-bay ECU or transmission controller board without derating for ambient heat.
PSRR profile — 90dB at 100Hz, 60dB at 100kHz
PSRR is listed at 90dB at 100Hz rolling off to 60dB at 100kHz. That 30dB drop across the audio band means the LDO rejects switching-regulator ripple well at low frequencies but passes more noise above 10kHz — a factor if the upstream converter runs at 500kHz, where the rejection is below the 60dB floor. For an automotive infotainment SoC core rail, this is still useful; for a 24-bit audio codec supply, you may want a second stage LC filter. Quiescent current is 25µA typical, with a maximum supply current of 425µA. The 25µA Iq keeps the battery drain low in always-on ECU domains, though the 425µA max at full load is the figure to budget for worst-case thermal on the 5.5V input rail. Dropout voltage is 0.25V max at 250mA load, so the input rail needs at least 2.05V to hold regulation at full current. The 5.5V abs-max input means the part survives a 12V battery cold-crank transient only with an external clamp — the internal FET does not take 12V.
Package and board-fit — SOT-23-5
Supplied in SC-74A / SOT-23-5 (the supplier device package is SOT-23-5). The 5-pin footprint is standard — the enable pin (active-high) lets the system power-cycle the rail without a separate load switch. Protection features cover over-temperature and short-circuit; no reverse-current protection is listed, so an output capacitor that holds charge when the input drops faster than the output may back-drive through the body diode.