300 mA, 3.3 V fixed LDO for under-hood automotive
The TPS78433QWDRBRQ1: Maximum dropout is 115 mV at the full 300 mA load, so the input rail needs to stay above 3.415 V across line and load to keep the output in regulation — a 3.3 V core rail fed from a 5 V bus has 1.585 V of headroom, well clear of the dropout floor. Quiescent current is 40 µA typical, which sets the always-on budget for an automotive ECU that never fully sleeps — a body controller drawing 40 µA from the battery for the regulator's own consumption adds about 0.96 mAh per day, negligible against a 60 Ah battery.
PSRR profile and noise rejection
Power-supply rejection ratio is specified as 60 dB at 1 kHz, rolling off to 30 dB at 1 MHz — the regulator attenuates 1 mV of 1 kHz ripple on the input to 1 µV at the output, but at 1 MHz the same ripple passes through at 31.6 µV. Upstream switching noise above a few hundred kHz needs a ferrite bead or a second LC stage ahead of the LDO to keep the output clean for sensitive analog loads.
Active production, AEC-Q100 compliance
The ROHS3 compliance certificate is available from Texas Instruments.