STMicroelectronics LDK320AU50R

Overview

LDK320AU50R from STMicroelectronics is a 5.0 V fixed-output, high-accuracy low-dropout linear regulator delivering up to 200 mA with 100 mV typical dropout at 100 mA, ±0.5% output voltage tolerance at 25 °C, and 88 dB PSRR at 120 Hz. It features logic-controlled shutdown (EN pin), operates from 2.5 V to 18 V input, and supports ceramic output capacitors as low as 1 μF - ideal for space-constrained, battery-powered DSC and industrial control modules.

For engineers reviewing the LDK320AU50R datasheet, LDK320AU50R pinout, LDK320AU50R application, or LDK320AU50R equivalent, this page delivers verified electrical specs, SOT23-5L package mapping, thermal protection behavior, EN logic thresholds, and design-meaningful load/line regulation values - all extracted from ST's DS11321 Rev 13.

Technical Context

The LDK320AU50R implements a bandgap-referenced op-amp control loop with internal current limiting, thermal shutdown (160 °C, 20 °C hysteresis), and SOA protection. Its architecture enables stable operation with 1 μF ceramic COUT across the full -40 °C to 125 °C junction temperature range.

It supports two distinct configurations: fixed-output (e.g., LDK320AU50R) using internal resistor divider, and adjustable version (LDK320ADJ) with ADJ pin - though the SOT23-5L package used by LDK320AU50R includes the EN and ADJ/NC pins, enabling precise enable timing and optional external feedback.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 1.25 mm max height, 2.92 mm × 2.80 mm footprint, exposed pad connected to GND for thermal enhancement.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with TLV70033DBVR and AP2210K-5.0TRG1, the LDK320AU50R uniquely combines 5.0 V ±0.5% accuracy, 100 mV dropout, integrated EN, and 88 dB PSRR - making it optimal for noise-sensitive, enable-sequenced, high-precision 5 V applications where headroom and stability are constrained.

Availability

LDK320AU50R is available at Aetrix Electronics and suitable for digital still cameras, industrial PLC I/O modules, Blu-ray player audio subsystems, and PC peripheral controllers requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for LDK320AU50R 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, designing and manufacturing microcontrollers, power management ICs, sensors, and analog devices for automotive, industrial, and consumer markets.

The LDK320 series belongs to ST's high-accuracy, low-noise LDO portfolio targeting battery-powered and noise-critical applications - engineered for minimal dropout, ultra-low quiescent current, and robust thermal protection in compact packages.

FAQ

What is the minimum input voltage required for LDK320AU50R to maintain regulation at full 200 mA load?

The LDK320AU50R requires VIN ≥ VOUT + VDROP. At 200 mA and 25 °C, VDROP is 200–350 mV (typ./max). Thus, minimum input is 5.0 V + 0.2 V = 5.2 V. Under worst-case conditions (125 °C, 200 mA), VDROP reaches 350 mV, so VIN ≥ 5.35 V is recommended for guaranteed regulation across temperature.

Can LDK320AU50R be used with a 10 μF ceramic output capacitor instead of the specified 1 μF?

Yes - the device is stable with 1–22 μF ceramic capacitors (per Table 6 and Figure 25). A 10 μF X7R 0603 capacitor improves transient response and reduces output impedance at higher frequencies, provided its ESR remains ≤1 Ω at 100 kHz. No compensation changes are needed.

Is the ADJ pin on LDK320AU50R functional or should it be left unconnected?

The ADJ pin is NC (No Connect) on the LDK320AU50R fixed-output variant. Per Table 1 and datasheet note, it must remain floating - connecting it to GND, VOUT, or any other node will disrupt regulation accuracy and may cause instability or overvoltage.

How does thermal shutdown behave during continuous overload, and what is the recovery mechanism?

When junction temperature reaches 160 °C, thermal shutdown activates, disabling the pass transistor and reducing output current to near zero. After shutdown, the device remains off until temperature drops by ≥20 °C (hysteresis), then automatically resumes regulation - no external reset or power cycle is required.