1.8V fixed rail, 100mA continuous — the supply spec that defines the fit
The TPS78918DBVR is a single-output positive linear regulator from Texas Instruments delivering a fixed 1.8V output at up to 100mA. The 10V maximum input gives enough headroom to regulate cleanly from a 5V or 3.3V intermediate bus without a separate pre-regulator stage. Quiescent current is 28 µA typical — low enough for always-on rails in battery-backed or standby domains where the regulator's own draw must stay under the system's sleep budget.
Power-supply rejection ratio is 85 dB at 1 kHz. This means switching ripple from a upstream DC-DC converter at typical 300 kHz to 2 MHz is attenuated by roughly 85 dB at the 1 kHz point; above that frequency the PSRR rolls off, so the actual attenuation at the switching fundamental depends on the output capacitor's impedance and the regulator's control-loop bandwidth. For a 1.8V rail feeding an ADC reference or a small-signal analog front-end, this level of rejection keeps supply-coupled noise below the converter's LSB threshold in most 12-bit to 14-bit signal chains. The enable pin lets the system power down the regulator externally — useful for sequencing multiple rails or cutting power to a sensor interface during sleep.
Active lifecycle, ROHS3, SOT-23-5 footprint
Packaged in a SOT-23-5 (SC-74A) surface-mount case, the footprint is standard and widely supported in assembly houses.