STMicroelectronics LD39050PU33R

Overview

LD39050PU33R from STMicroelectronics is a 500 mA ultra-low-dropout linear voltage regulator with fixed 3.3 V output, 200 mV typical dropout at full load, 20 µA typical quiescent current at no load, ±2.0% output voltage tolerance at 25 °C, and stable operation with 1 µF ceramic output capacitor. It serves as a primary power rail for low-power microcontrollers and RF subsystems in battery-powered portable electronics.

For engineers reviewing the LD39050PU33R datasheet, LD39050PU33R pinout, LD39050PU33R application, or LD39050PU33R equivalent, key selection criteria include dropout performance under 500 mA load, sub-1 µA shutdown current, Power Good (PG) monitoring capability, and compatibility with small-footprint DFN6 (2x2 mm) packaging for space-constrained designs.

Technical Context

The LD39050PU33R implements a PMOS pass transistor architecture enabling ultra-low dropout voltage and near-zero reverse current during shutdown. Its internal bandgap reference and error amplifier deliver tight DC regulation across -40 °C to 125 °C junction temperature.

It integrates logic-controlled enable (EN), open-drain Power Good (PG) with 92% VOUT rising threshold, thermal shutdown at 160 °C with 20 °C hysteresis, and constant-current short-circuit protection. The device achieves 65 dB PSRR at 1 kHz and maintains stability with 1–22 µF ceramic capacitors without external compensation.

Key Specifications

Pinout & Package

LD39050PU33R uses the DFN6 (2x2 mm) package with exposed thermal pad, optimized for compact PCB layouts and efficient heat dissipation in high-density applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G and RT9013-33GB, LD39050PU33R uniquely combines 500 mA capability, sub-1 µA shutdown, integrated PG, and DFN6 (2x2 mm) packaging - making it optimal for space- and power-critical embedded systems requiring verified rail integrity.

Availability

LD39050PU33R is available at Aetrix Electronics and suitable for wearable health monitors, industrial IoT sensor nodes, automotive cabin cameras, and portable medical ultrasound probes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LD39050PU33R 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, specializing in power management, microcontrollers, and automotive-grade ICs with broad industrial and consumer reach.

The LD39050 belongs to ST's high-efficiency, low-noise LDO portfolio designed specifically for battery-powered and noise-sensitive applications where ultra-low I_Q, small form factor, and rail-monitoring capability are essential.

FAQ

What is the minimum input voltage required for LD39050PU33R to regulate 3.3 V output?

The LD39050PU33R requires a minimum input voltage of 3.5 V to sustain 3.3 V output at 500 mA load, based on its 200 mV typical dropout voltage specification. At lighter loads, regulation is possible down to 3.35 V input; however, operation below 3.5 V should be verified against worst-case 400 mV max dropout across temperature and process variation.

Can LD39050PU33R be used with a 1 µF ceramic output capacitor?

Yes - the LD39050PU33R is explicitly characterized and guaranteed stable with a 1 µF X5R or X7R ceramic capacitor on the output, as confirmed in Table 5 and Figure 33–34 of the datasheet. This eliminates the need for larger or more expensive capacitor types and simplifies layout.

Does LD39050PU33R provide reverse current protection?

Yes - the PMOS pass transistor architecture inherently blocks reverse current flow from VOUT to VIN when the input is disconnected or falls below the output voltage. This prevents backfeeding and protects upstream sources such as batteries or USB ports during hot-swap or fault conditions.

How does the Power Good (PG) pin behave during startup and dropout?

The PG pin asserts high when VOUT reaches ≥92% of 3.3 V and remains high until VOUT drops to ≤80% of 3.3 V. During startup, PG goes high after output settles within tolerance; during input brownout, PG pulls low before regulation is lost - providing early warning for controlled system shutdown.