STMicroelectronics LDK320ADU50R

Overview

LDK320ADU50R from STMicroelectronics is a 5.0 V fixed-output, high-accuracy (±0.5% at 25 °C), low-dropout linear regulator delivering up to 200 mA with 100 mV typical dropout at 100 mA load, operating from 2.5 V to 18 V input. It features logic-controlled shutdown (EN pin), 88 dB PSRR at 120 Hz, and stable operation with 1 μF ceramic output capacitor. Designed for space-constrained, battery-powered consumer electronics requiring precision voltage regulation.

For engineers reviewing the LDK320ADU50R datasheet, LDK320ADU50R pinout, LDK320ADU50R application, or LDK320ADU50R equivalent, key selection criteria include output accuracy over temperature, ultra-low quiescent current (60 μA typ.), thermal/short-circuit protection, and compatibility with SOT23-5L packaging for compact PCB layouts.

Technical Context

The LDK320ADU50R implements a bandgap-referenced op-amp control loop with internal bias generator and thermal shutdown circuitry (trip point 160 °C, 20 °C hysteresis). Its EN pin provides active-high logic control enabling sub-1 μA off-mode current consumption.

It supports two package variants: SOT23-5L (with IN, GND, EN, ADJ/NC, OUT pins) and SOT-89 (D configuration: GND, IN, OUT, TAB–IN), though the ADU50R marking confirms this variant is the fixed 5.0 V version in SOT23-5L - where Pin 4 is NC and not connected.

Key Specifications

Pinout & Package

SOT23-5L package: 2.92 mm × 2.80 mm × 1.25 mm body, 0.95 mm pitch, thermally enhanced with exposed pad tied to GND (per mechanical data).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout, fixed-output voltage regulator applications.

Compared with TLV70550DBVR and MCP1703T-5002E/MB, the LDK320ADU50R uniquely balances ±0.5% accuracy, 100 mV dropout, and integrated thermal hysteresis - making it optimal for industrial and consumer devices needing precision, efficiency, and ruggedness in one SOT23-5L package.

Availability

LDK320ADU50R is available at Aetrix Electronics and suitable for digital still cameras, Blu-ray players, industrial HMIs, and USB peripherals requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LDK320ADU50R includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for automotive, industrial, and consumer markets.

The LDK320 series belongs to ST's high-accuracy, low-quiescent-current LDO portfolio, engineered specifically for battery-powered and space-constrained applications demanding tight regulation, low noise, and robust protection without external components.

FAQ

What is the maximum output current and corresponding dropout voltage for LDK320ADU50R?

The LDK320ADU50R delivers up to 200 mA output current. At 100 mA load and 25 °C, its typical dropout voltage is 100 mV; at 200 mA, it rises to 200–350 mV depending on junction temperature. This low dropout enables operation from inputs as low as 5.1 V while maintaining regulated 5.0 V output.

Can LDK320ADU50R be used with ceramic output capacitors smaller than 1 µF?

No - the datasheet specifies a minimum 1 µF ceramic capacitor (X5R/X7R, ESR ≤1 Ω) for stability. Using smaller values risks oscillation or poor transient response. The device is optimized for 1–22 µF range; 1 µF is the validated lower bound for guaranteed phase margin across temperature and load conditions.

Does LDK320ADU50R require an input capacitor, and if so, what value?

While not strictly mandatory for stability, a 1 µF ceramic input capacitor placed near the IN pin is strongly recommended to reduce high-frequency noise and improve line transient response. It mitigates impedance spikes from upstream sources and enhances PSRR above 10 kHz, especially when fed from switchers or long PCB traces.

How does the EN pin behave under partial voltage or slow-rising signals?

The EN pin has defined thresholds: logic low ≤0.4 V (shutdown), logic high ≥1.2 V (active), with hysteresis ensured by internal design. Slow-rising EN signals are tolerated; the device transitions cleanly between states without chatter. Input leakage is ≤100 nA, allowing direct connection to microcontroller GPIO without pull-up/down resistors.