500 mA output, 40 V input – the headroom decision
The TPS7B8850QKVURQ1R2: The 0.575 V dropout at full load means the input must stay above 5.575 V to hold regulation; a 12 V battery dipped to 6 V during cold crank still leaves margin.
AEC-Q100 Grade 1 – 125°C junction for under-hood deployment
The 40 V abs-max input covers load-dump transients without an external clamp, and the integrated over-current, over-temperature, and UVLO protection circuits handle fault conditions autonomously. The 26 µA quiescent current keeps the always-on draw low enough that a 12 V battery parked for a month loses less than 0.02 Ah to the regulator alone – relevant for modules that stay powered during ignition-off.
70 dB PSRR at 1 kHz – filtering switching noise
The 70 dB power-supply rejection ratio at 1 kHz attenuates ripple from a downstream DC-DC converter by a factor of 3160. For a 5 V rail feeding an analog sensor or ADC reference, this keeps the supply-induced noise floor below 10 µV – the regulator's own output noise, not the input ripple, becomes the limit.
TO-252 package – thermal pad and board layout
Housed in a TO-252-3 (DPak) surface-mount package with an exposed metal tab on the bottom side. The tab is the output terminal and the primary heat path – the PCB copper area under it sets the junction-to-ambient thermal resistance.