Adjustable LDO for 800 mA rails — what the ratings mean
The LD1117SC-R is an adjustable positive LDO from the LD1117 family, delivering up to 800 mA with a dropout voltage of 1.3 V max at that full load. That dropout means your input rail must stay at least 1.3 V above the set output voltage under worst-case current — for a 3.3 V output, Vin must be ≥ 4.6 V. The output adjusts from 1.25 V up to 15 V using two external resistors. PSRR is 75 dB at 120 Hz — strong rejection of the fundamental ripple from a rectified AC line or a switching pre-regulator. For comparison, the ST LDFPVR sibling delivers 62 dB to 55 dB across 120 Hz to 100 kHz, so the LD1117SC-R holds a clear advantage at line-frequency rejection. Quiescent current is 5 mA — not a micropower part, but acceptable for many post-regulation stages where the load current dominates the efficiency budget.
ROHS3 compliant.
Housed in a SOT-223 (TO-261AA) surface-mount package. Protection features include over-current and over-temperature shutdown.