STMicroelectronics LDLN050PU33R

Overview

LDLN050PU33R from STMicroelectronics is a 500 mA, fixed 3.3 V output low-dropout linear regulator in DFN8 (3 × 3 mm) package, featuring 13 µV_RMS/V_OUT output noise, 190 mV dropout at full load, and 48 µA typical quiescent current. It employs a PMOS pass element for fast turn-on and integrates current limit and thermal protection, targeting noise-sensitive industrial power rails for MCUs and wireless ICs.

For engineers reviewing the LDLN050PU33R datasheet, LDLN050PU33R pinout, LDLN050PU33R application, or LDLN050PU33R equivalent, key selection considerations include its 3.3 V fixed output with CNR pin for noise reduction, -40 °C to 125 °C operating range, 65 dB PSRR at 100 Hz, and compatibility with ≥2 µF low-ESR ceramic output capacitors.

Technical Context

The LDLN050PU33R implements a PMOS-based LDO architecture with internal bandgap reference, UVLO (2.2 V threshold), and quick-start circuitry for fixed-output variants. Its NR pin accepts an external capacitor to suppress high-frequency output noise, enabling sub-15 µV_RMS performance at 3.3 V output.

Thermal protection triggers at 165 °C with 20 °C hysteresis, and the enable input requires explicit logic-level control (V_EN(H) = 1.2 V min) without internal pull-up. The device maintains regulation across 2.7–6.5 V input while delivering ±2% output accuracy over 1–500 mA load and -40–125 °C ambient.

Key Specifications

Pinout & Package

LDLN050PU33R is housed in a thermally enhanced DFN8 (3 × 3 mm, 0.85 mm height) package with exposed thermal pad requiring GND connection. Pin 1 is OUT; pins 2 and 6–7 are no-connect; pin 3 serves as NR (Noise Reduction) for fixed-output configuration; pin 4 is GND; pin 5 is EN; pin 8 is IN; exposed pad is thermal ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G, LDLN050PU33R delivers 2× output current and 40% lower noise via CNR pin; versus ADM7172ACPZ-3.3-R7, it trades 1.5 A capacity and sub-4 µV noise for 5× lower IQ and smaller DFN8 footprint - optimizing for industrial IoT size/power/noise balance.

Availability

LDLN050PU33R is available at Aetrix Electronics and suitable for industrial sensor nodes, wireless MCU power rails, and PLC digital I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LDLN050PU33R 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 silicon solutions for automotive, industrial, and power management applications.

The LDLN050 series belongs to ST's high-performance LDO portfolio, engineered specifically for noise-critical industrial and wireless applications where low IQ, fast transient response, and thermal robustness are essential.

FAQ

What is the minimum input voltage required for LDLN050PU33R to regulate at full 500 mA load?

The minimum input voltage is calculated as V_OUT + V_DO = 3.3 V + 0.19 V = 3.49 V. Per datasheet Table 5, dropout is specified at 190 mV typical (500 mV max) under those conditions. Input below 3.49 V will cause dropout mode and unregulated output.

Can the NR pin be left unconnected on LDLN050PU33R?

No. The NR pin must be connected to a capacitor (1–47 nF) between NR and GND to achieve the specified 13 µV_RMS/V_OUT noise performance. Leaving it open increases output noise to 25 µV_RMS/V_OUT, degrading performance in noise-sensitive applications.

Does LDLN050PU33R require an input capacitor, and what value is recommended?

Yes - a minimum 1 µF X7R ceramic capacitor is required at the IN pin, placed as close as possible to the device. This stabilizes the input impedance and prevents oscillation during load transients, especially when sourced from high-impedance or switching supplies.

How does the thermal pad connection affect LDLN050PU33R's power dissipation capability?

The exposed thermal pad must be soldered to a dedicated GND copper pour with ≥4 thermal vias (0.3 mm diameter) to an inner ground plane. Without this, R_thJA rises from 51 °C/W to >100 °C/W, limiting continuous power dissipation to <0.3 W instead of the rated 0.6 W at 25 °C ambient.