Package and board integration — SOT-223 with exposed pad
The IFX1117GSV33: For 1 A continuous output, the copper area under the tab sets the junction-to-ambient thermal resistance — a 1-square-inch pad on a 2-layer board keeps the die below 125°C at full load with 5 V input-to-output differential.
Dropout and input headroom — the 1.4 V ceiling at full load
Maximum dropout voltage is 1.4 V at 1 A output — the input rail must stay at least 4.7 V to maintain 3.3 V regulation under worst-case conditions. With a 15 V absolute maximum input, the part tolerates 12 V intermediate rails and 5 V rails with margin for transients.
PSRR at 120 Hz — filtering the rectified line ripple
Power supply rejection ratio is 65 dB at 120 Hz, which attenuates the 100/120 Hz ripple from a full-wave rectified mains supply by a factor of roughly 1800 — a 1 Vpp ripple at the input becomes about 0.55 mVpp at the output.
Protection and quiescent budget
Built-in overcurrent, overtemperature, and short-circuit protection eliminate the need for external supervisory circuits on the output rail. Quiescent current is 10 mA — this is the standing draw from the input rail when the output is unloaded, relevant for always-on or battery-backed rails where every milliamp counts.
Lifecycle and compliance — active and ROHS3
ROHS3 compliant — the part contains none of the six restricted substances plus the four phthalates under EU Directive 2011/65/EU, so it ships without a RoHS exemption statement.