500 mA adjustable LDO — PSRR and dropout that matter for noise-sensitive rails
The Renesas RAA2142504GSP#HA0 is a 500 mA low-dropout regulator with an adjustable output from 1.224 V up to 18 V, supplied in an 8-SOIC exposed-pad package. It operates from a maximum 20 V input rail. PSRR spans 87 dB at 100 Hz down to 63 dB at 10 kHz — this is the band where switching-regulator ripple and line-frequency hum live, so the LDO cleans up post-regulated rails for sensitive analog loads without requiring an additional LC filter stage. Maximum dropout is 0.45 V at the full 500 mA load — the headroom between input and output must stay above 450 mV across line and load to keep the output in regulation; below that threshold the pass element enters the linear region and PSRR collapses.
Temperature grade and protection set for industrial environments
Integrated over-current, over-temperature, and short-circuit protection cover the common failure modes — a sustained output short on a 20 V rail pulls the die temperature up until the thermal-shutdown latch trips, then the part cycles back when the junction cools. Quiescent supply current is 225 µA maximum — the regulator's own draw stays below the self-discharge rate of a typical 100 mAh coin cell, making it viable for always-on sensor nodes that wake periodically to sample and transmit.
Package and layout — the exposed pad is the thermal path
The 8-SOIC with exposed pad (8-SOIC-EP) requires a thermal land on the PCB — the die attaches directly to the paddle, and the datasheet's RθJA of roughly 40-50°C/W (depending on copper area and layer count) assumes a soldered pad with vias to an internal ground plane. Enable control (active-high) lets the system processor gate the output rail during sleep — when pulled low, the LDO draws near-zero quiescent current and the output discharges through the internal pull-down. The adjustable output uses an external resistor divider from VOUT to ADJ; the internal reference is 1.224 V. The feedback pin's bias current is low enough that 10 kΩ divider resistors keep the set-point error under 1% across temperature.