The MIC5209YU-TR is a single-output adjustable positive LDO regulator from Microchip Technology, delivering up to 500 mA continuous output current from a 16 V maximum input rail. Output voltage is adjustable from a 1.8 V reference up to 15 V, set by an external resistor divider — the 1.8 V minimum fixed output is the bandgap floor, not a regulation limit. Dropout voltage is 0.6 V maximum at the full 500 mA load, so the input rail must stay at least 600 mV above the programmed output across the load range to maintain regulation. Quiescent current is 170 µA typical, rising to 25 mA maximum under supply — the low Iq keeps the part viable for always-on rails in battery-powered equipment where every microamp counts.
PSRR and noise-sensitive rail performance
For an analog front-end powered from a switching preregulator, the 75 dB at 120 Hz is the low-frequency floor; above the crossover frequency the PSRR rolls off, so the switching noise at 100 kHz–1 MHz passes through with less attenuation unless post-filtered.
Protection and control features
On-chip protection includes overcurrent limiting, overtemperature shutdown, and reverse polarity protection — the reverse polarity clamp means the regulator survives a reversed input without external Schottky, saving a diode drop and a component on the BOM. An Enable pin (active-high) allows the output to be gated by a logic signal; when pulled low the regulator enters shutdown with near-zero quiescent draw, useful for sequenced power-up or sleep-mode power gating.
Package and thermal management
The TO-263-5 (D²Pak) surface-mount package has an exposed metal tab on the bottom — the tab is the main heat path, and the board copper area under it sets the junction-to-ambient thermal resistance.
Lifecycle and compliance
ROHS3 compliant (directive 2015/863), with no restricted substances above the threshold limits; the part carries no halogenated flame retardants and is suitable for lead-free reflow profiles.