300 mA LDO with 15 µA quiescent current
The TPS7A2009PDBVR is a single-output, positive fixed LDO from Texas Instruments, delivering 300 mA continuous output at a fixed 0.9 V. Its 15 µA quiescent current makes it a fit for always-on rails in battery-powered or energy-conscious designs — the regulator's own draw stays below 20 µA even at light load, preserving standby budget.
PSRR profile and noise rejection
PSRR is specified at 65 dB at 100 Hz, rolling off to 40 dB at 1 MHz. This means the LDO attenuates low-frequency ripple from a switching pre-regulator by a factor of ~1800 at 100 Hz, but above 100 kHz the rejection drops to about 100× — upstream noise above that corner passes through unless filtered ahead of the LDO input.
Dropout and headroom
Maximum dropout voltage is 0.69 V at 300 mA load. The input rail must stay at least 0.69 V above the 0.9 V output across the full load range — a 1.8 V supply provides 0.9 V headroom, well within the 6 V maximum input rating. Below the dropout threshold the output falls out of regulation.
Temperature range and protection
Rated for -40°C to 125°C junction temperature, covering industrial and automotive ambient conditions. On-chip protection includes over-current, over-temperature, and under-voltage lockout (UVLO). The enable pin allows external sequencing; the soft-start feature limits inrush current during power-up.