STMicroelectronics LDLN025M18R

Overview

LDLN025M18R from STMicroelectronics is a 250 mA ultra-low-noise low-dropout (LDO) voltage regulator in SOT23-5L package, delivering 1.8 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 250 mA, and features 6.5 µVRMS output noise and 80 dB PSRR at 100 Hz-optimized for powering noise-sensitive RF modules and image sensors.

For engineers reviewing the LDLN025M18R datasheet, LDLN025M18R pinout, LDLN025M18R application, or LDLN025M18R equivalent, this LDO is selected for battery-powered portable systems requiring stable 1.8 V rail, minimal quiescent current (12 µA no-load), logic-controlled shutdown, and ceramic-capacitor compatibility without external compensation.

Technical Context

The LDLN025M18R employs a bandgap-referenced error amplifier with internal soft-start and controlled quiescent current regulation during dropout. Its bias generator and thermal protection circuitry enable operation from –40 °C to +125 °C junction temperature while maintaining <1 µA shutdown current.

Designed for high-PSRR, low-noise performance, it integrates output discharge, overcurrent limiting, and thermal shutdown. The EN pin (internally pulled down) accepts logic-level control, and the exposed pad must be connected to GND for thermal and electrical integrity.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 2.95 mm × 1.60 mm × 1.45 mm body, exposed thermal pad (must be soldered to GND plane).

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B182MR-G and ADP160ACBZ-1.8-R7, LDLN025M18R uniquely balances 250 mA drive, 6.5 µVRMS noise, integrated discharge, and full thermal/overcurrent protection-making it optimal for compact, high-performance portable RF and imaging systems.

Availability

LDLN025M18R is available at Aetrix Electronics and suitable for smartphone power management, image sensor biasing, portable instrumentation, and industrial IoT sensor nodes requiring stable component supply with guaranteed long-term continuity.

Supply support for LDLN025M18R 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, analog, and microcontroller solutions for automotive, industrial, and consumer markets.

The LDLN025 series belongs to ST's ultra-low-noise LDO product line, engineered specifically for powering noise-critical analog and RF circuits in space-constrained portable electronics.

FAQ

What is the minimum input voltage required for LDLN025M18R to regulate at 1.8 V?

The LDLN025M18R requires VIN ≥ VOUT + dropout voltage. At 250 mA load, dropout is 250 mV (SOT23-5L), so minimum VIN = 2.05 V. At light loads (<1 mA), dropout drops to ~50 mV, allowing regulation down to 1.85 V. Absolute minimum VIN per datasheet is 1.5 V, but regulation is not guaranteed below VOUT + dropout.

Can LDLN025M18R be used with 0.1 µF output capacitors?

No. The datasheet specifies minimum COUT = 0.7 µF (X7R ceramic) for stability across all operating conditions. Using 0.1 µF violates the stability region defined in Figure 19 and risks oscillation, especially under load transients. Always use ≥0.7 µF with ESR between 5 mΩ and 500 mΩ.

Is the exposed pad on the SOT23-5L package electrically connected?

Yes. The exposed pad is internally connected to GND and must be soldered to a PCB GND plane for both electrical functionality and thermal performance. Leaving it floating degrades thermal resistance (R_thJA increases from 200 °C/W to >300 °C/W) and may cause instability or premature thermal shutdown.

Does LDLN025M18R support reverse current blocking?

No. The LDLN025M18R does not include reverse current blocking. If VIN falls below VOUT (e.g., during hot-swap or backup battery switchover), current can flow backward from VOUT to VIN through the pass transistor. External reverse-blocking diodes or MOSFETs are required in such architectures.