STMicroelectronics LDLN025PU32R

Overview

LDLN025PU32R from STMicroelectronics is a 250 mA ultra-low-noise low-dropout (LDO) voltage regulator in DFN4-1x1 package, delivering 3.2 V output with ±2% accuracy across line, load, and temperature. It operates from 1.5 V to 5.5 V input, achieves 250 mV dropout at full 250 mA load, and features 6.5 μVRMS output noise (10 Hz–100 kHz) and 80 dB PSRR at 100 Hz-optimized for powering noise-sensitive RF and analog circuits.

For engineers reviewing the LDLN025PU32R datasheet, LDLN025PU32R pinout, LDLN025PU32R application, or LDLN025PU32R equivalent, this LDO is selected for battery-powered instrumentation, image sensor biasing, VCO supply rails, and high-precision ADC reference domains where quiescent current (<12 μA no-load), thermal stability (−40 °C to +125 °C), and ceramic-capacitor compatibility are critical.

Technical Context

The LDLN025PU32R uses a bandgap-referenced PMOS pass transistor architecture with internal soft-start, logic-controlled enable (VEN = 1.2 V threshold), and output discharge (230 Ω internal resistor). Its bias generator maintains controlled quiescent current even in dropout-critical for extending runtime in deep-sleep mobile systems.

Stability is guaranteed with 0.7–1 μF ceramic input/output capacitors (ESR 5–500 mΩ); the device integrates overcurrent limiting, thermal shutdown at 160 °C (20 °C hysteresis), and ESD protection (±2000 V HBM). It supports three package variants-DFN4-1x1, Flip-Chip4, and SOT23-5L-with identical electrical specs but distinct thermal resistance (R_thJA = 220 °C/W for DFN4-1x1).

Key Specifications

Pinout & Package

LDLN025PU32R is packaged in DFN4-1x1 (1.0 mm × 1.0 mm × 0.38 mm), featuring an exposed thermal pad that must be soldered to PCB ground for optimal thermal performance (R_thJA = 220 °C/W). The 4-pin configuration excludes NC and integrates GND directly under the die for low-inductance return path.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-noise LDO applications.

Compared with XC6210B322MR-G and ADP125ARHZ-3.2-R7, LDLN025PU32R uniquely combines 250 mA capability, 6.5 μVRMS noise, integrated output discharge, and DFN4-1x1 footprint-making it optimal for space-constrained, battery-operated RF/analog systems requiring best-in-class noise and efficiency trade-offs.

Availability

LDLN025PU32R is available at Aetrix Electronics and suitable for smartphone image sensor biasing, VCO power supply, portable instrumentation ADC reference, and wireless LAN transceiver LNA bias applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LDLN025PU32R 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 microcontrollers, power management ICs, sensors, and analog components for automotive, industrial, and consumer markets.

The LDLN025 series belongs to ST's ultra-low-noise LDO product line, engineered specifically for powering noise-sensitive RF, imaging, and precision analog subsystems in battery-operated portable electronics.

FAQ

What is the minimum input voltage required for LDLN025PU32R to regulate 3.2 V output?

The LDLN025PU32R requires VIN ≥ VOUT + dropout voltage. At 250 mA and 125 °C, dropout is 250 mV, so minimum VIN is 3.45 V. However, per datasheet Table 4, the operating input range starts at 1.5 V-meaning it can regulate 3.2 V only when VIN ≥ 3.45 V under full load and worst-case temperature. For light loads, regulation begins at lower VIN due to reduced dropout.

Can LDLN025PU32R be used with 0.47 μF output capacitors?

No-0.47 μF is below the minimum recommended COUT of 0.7 μF specified in Table 5. Using undersized capacitance risks instability, especially under load transients, as confirmed by Figure 19's stability region (COUT ≥ 0.7 μF required for ESR 5–500 mΩ). Always use ≥0.7 μF X7R/X5R ceramic capacitors.

Does the exposed pad on the DFN4-1x1 package require solder mask opening?

Yes-the exposed thermal pad (shown in Figure 34) must be fully exposed and soldered to a dedicated PCB copper pour connected to GND. ST recommends a 0.35 mm × 0.35 mm stencil aperture and ≥80% solder paste coverage. Omitting this compromises thermal performance (R_thJA degrades from 220 to >300 °C/W) and increases junction temperature risk.

Is the EN pin internally pulled down on LDLN025PU32R?

Yes-Table 1 specifies a 1 MΩ internal pull-down resistor on the EN pin. This ensures default shutdown (I_Q < 1 μA) when the pin is left unconnected or driven high-impedance. To enable the device, drive EN ≥ 1.2 V with a logic signal capable of sourcing ≥5.5 μA (per Table 4 I_EN spec).