0.8V fixed rail for automotive sensor chains
The TPS78408QDBVRQ1 is a single-output positive LDO from Texas Instruments, part of the Automotive AEC-Q100 series. It delivers a fixed 0.8V output at up to 300mA continuous, with a maximum dropout voltage of 0.775V at full load. The 150°C junction temperature rating places this regulator in the under-hood / engine-bay class — a 125°C part would not survive the same thermal profile. The 30 µA quiescent current keeps the standing loss low on always-on battery rails.
PSRR is specified at 60 dB at 1 kHz, rolling to 30 dB at 1 MHz. That 30 dB floor at 1 MHz is the relevant number for switching-regulator ripple at 2–3 MHz — the LDO still attenuates by a factor of ~31× at that frequency. Below 100 kHz the attenuation is substantially higher. Dropout of 0.775V max at 300 mA means the input rail must stay above 1.575V to maintain regulation at full load. For a 3.3V input bus, that leaves 1.725V headroom — comfortable margin even with the 6V absolute maximum.
Active production — no LTB clock ticking
The SOT-23-5 package is a standard footprint shared across many TI LDOs, easing second-source planning. No stock-holding claim; the part is quoted to order.