STMicroelectronics LD39050PU25R

Overview

LD39050PU25R from STMicroelectronics is a 500 mA ultra-low-dropout linear voltage regulator with fixed 2.5 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 low-noise power supply for battery-powered microcontroller cores and RF subsystems in portable electronics.

For engineers reviewing the LD39050PU25R datasheet, LD39050PU25R pinout, LD39050PU25R application, or LD39050PU25R equivalent, key selection criteria include dropout voltage under 500 mA load, sub-1 µA shutdown current, Power Good (PG) open-drain monitoring capability, and compatibility with small-footprint DFN6 (2x2 mm) packaging for space-constrained designs.

Technical Context

The LD39050PU25R implements a PMOS pass transistor architecture enabling ultra-low dropout and near-zero reverse current during shutdown. Its internal bandgap reference and error amplifier deliver tight DC regulation across –40 °C to 125 °C, while the PG pin provides programmable power-good threshold (92% rising / 80% falling of VOUT) for system sequencing.

It integrates thermal shutdown (160 °C trip, 20 °C hysteresis) and constant-current short-circuit protection (600–800 mA), and achieves 65 dB PSRR at 1 kHz without requiring external bypass capacitors-critical for noise-sensitive analog and RF rails.

Key Specifications

Pinout & Package

LD39050PU25R uses the DFN6 (2x2 mm) package with exposed thermal pad, optimized for high-density PCB layouts and efficient heat dissipation in thin-profile handheld devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B252MR-G and BD39050MUV-E2, the LD39050PU25R uniquely combines PG programmability, highest PSRR, and industry-leading noise performance-making it optimal for mixed-signal systems demanding both precision and reliability.

Availability

LD39050PU25R is available at Aetrix Electronics and suitable for mobile phone baseband power, wearable sensor hub regulation, and industrial IoT gateway design requiring stable component supply across long product lifecycles.

Supply support for LD39050PU25R 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 specializing in power management, microcontrollers, and analog ICs for automotive, industrial, and consumer markets.

The LD39050 belongs to ST's high-efficiency, low-noise LDO portfolio designed specifically for battery-powered and space-constrained applications demanding ultra-low IQ and precise voltage regulation.

FAQ

What is the minimum input voltage required for stable 2.5 V output at 500 mA?

The LD39050PU25R requires VIN ≥ VOUT + VDROP = 2.5 V + 0.2 V = 2.7 V for full 500 mA output. At lower input voltages, output current is reduced per the dropout curve in Figure 9; operation below 1.5 V input is not supported.

Can the PG pin drive an MCU GPIO directly without a pull-up resistor?

No-the PG pin is open-drain and requires an external pull-up resistor (typically 10–100 kΩ to VIN or VCC) to generate a valid logic-high signal. The datasheet specifies it sinks up to 6 mA when asserted low, compatible with most 1.8 V/3.3 V GPIO inputs.

Is the DFN6 (2x2 mm) package thermally adequate for continuous 500 mA operation at 85 °C ambient?

Yes-R_thJA = 65 °C/W and R_thJC = 6.5 °C/W allow ~1.25 W power dissipation. At 500 mA and 200 mV dropout, P_D = 100 mW, resulting in <10 °C junction rise above ambient-well within the 125 °C max rating even with minimal copper pour.

Does the 30 µV_RMS noise specification apply across all load currents?

Yes-the 30 µV_RMS (10 Hz–100 kHz) value is specified at IOUT = 100 mA, but typical performance curves (Figure 24) show noise remains ≤35 µV_RMS from 1 mA to 500 mA, confirming consistent low-noise behavior across its operating range.