800 mA adjustable LDO — SOT-223 footprint
The LD1117STR is an 800 mA positive adjustable LDO from STMicroelectronics, built around a 1.25 V reference. At full load the dropout is 1.2 V max, meaning the input must stay at least 1.2 V above the output voltage to maintain regulation.
PSRR and quiescent current
PSRR is 75 dB at 120 Hz — a strong figure for an 800 mA LDO, useful for cleaning ripple from a rectified AC rail or a switching pre-regulator. Quiescent current is 5 mA, which is modest; the trade-off is that the pass transistor is biased for low dropout rather than low Iq. The adjustable output range runs from 1.25 V up to 15 V, limited only by the input headroom and the 15 V input max.