Cleaning up a sensitive analog rail
The TPS7A2009PDQNR is a 300 mA LDO from Texas Instruments, fixed at 0.9 V output, designed to deliver a clean supply rail for noise-sensitive analog and RF stages. Its PSRR holds 65 dB at 100 Hz and drops to 40 dB at 1 MHz, meaning it rejects ripple from a switching pre-regulator across the audio band and well into the low-MHz region — exactly what a sensitive ADC or PLL VCO needs to keep jitter and spurs off the supply.
Battery-life budget and dropout margin
Quiescent current is 15 µA typical — low enough that the regulator's own draw won't dominate the sleep current in a battery-powered sensor node that spends most of its time in deep sleep. Maximum dropout voltage is 0.69 V at the full 300 mA load, so the input rail needs to stay above roughly 1.6 V to maintain regulation at 0.9 V out — a single Li-ion cell near end-of-discharge (3.0 V) still has ample headroom. The enable pin lets a system controller power down the regulator when the load is idle, cutting total draw to near zero.
Thermal and protection for a tight board
Built-in over-current, over-temperature, and UVLO protection mean the part can survive a brief output short or a hot environment without latching up or failing open.
RoHS3 compliant and supplied on tape & reel or cut tape, it integrates into standard lead-free reflow processes without a separate bake if the moisture-sensitive level (MSL) rating is observed.