STMicroelectronics LDLN025M33R

Overview

LDLN025M33R from STMicroelectronics is a 250 mA ultra-low-noise low-dropout (LDO) voltage regulator in SOT23-5L package, delivering 3.3 V output with ±2% accuracy across line, load, and temperature. It operates from 1.5 V to 5.5 V input, achieves 120 mV typical dropout at 250 mA, and features 6.5 µV_RMS output noise (10 Hz–100 kHz) and 80 dB PSRR at 100 Hz-optimized for powering noise-sensitive RF modules and image sensors.

For engineers reviewing the LDLN025M33R datasheet, LDLN025M33R pinout, LDLN025M33R application, or LDLN025M33R equivalent, this LDO is selected for battery-powered portable systems requiring stable 3.3 V rail, minimal quiescent current (12 µA no-load), logic-controlled shutdown (<1 µA off-state), and ceramic-capacitor compatibility without external compensation.

Technical Context

The LDLN025M33R employs a bandgap-referenced error amplifier with internal soft-start and controlled quiescent current regulation-even in dropout-to extend runtime in deep-discharge battery operation. Its bias generator and thermal protection circuitry enable robust operation from –40 °C to +125 °C junction temperature.

Designed for high-PSRR, low-noise performance, it integrates output discharge, overcurrent limiting, and thermal shutdown. The EN pin features internal 1 MΩ pull-down and logic-level thresholds (V_IL ≤ 0.4 V, V_IH ≥ 1.2 V), supporting direct interfacing with microcontrollers and PMICs.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 2.95 mm × 1.60 mm × 1.45 mm body, exposed pad not present (unlike DFN/Flip-Chip variants). Requires standard SOT23-5 footprint per DS11756 Rev 8 Figure 37.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G and ADP160AUJZ-3.3-R7, LDLN025M33R uniquely combines 250 mA drive, 6.5 µV_RMS noise, and integrated EN-making it the only drop-in option for compact, high-performance 3.3 V rails in portable RF and imaging systems.

Availability

LDLN025M33R is available at Aetrix Electronics and suitable for smartphone RF modules, industrial image sensors, portable medical devices, and IoT wireless nodes requiring stable component supply with guaranteed long-term manufacturability.

Supply support for LDLN025M33R 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 consumer markets since 1987.

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, battery-operated portable electronics.

FAQ

What is the minimum input voltage required for LDLN025M33R to regulate 3.3 V output?

The LDLN025M33R requires VIN ≥ VOUT + dropout voltage. With 120 mV typical dropout at 250 mA, minimum VIN is 3.42 V under full load. At light load (1 mA), dropout drops to ~50 mV, allowing regulation down to 3.35 V. Absolute minimum VIN per datasheet is 1.5 V-but regulation only occurs when VIN exceeds VOUT by the applicable dropout margin.

Can LDLN025M33R be used with 0.47 µF output capacitors?

No-0.47 µF is below the minimum recommended COUT of 0.7 µF per Table 5. Using undersized capacitance risks instability and degraded PSRR/noise performance. The device is optimized for 1 µF ceramic (X7R/X5R), with stable operation confirmed up to 10 µF and ESR between 5 mΩ and 500 mΩ.

Does the NC pin on SOT23-5L require PCB connection?

Pin 4 (NC) is not internally connected and has no electrical function. ST's datasheet states it "can be connected to GND" for mechanical reinforcement-this is optional and does not affect regulation, noise, or thermal performance. Leaving it floating is electrically acceptable but may reduce solder joint reliability in high-vibration environments.

How does thermal shutdown behave during sustained overload?

Thermal shutdown activates at TJ = 160 °C with 20 °C hysteresis (re-enable at ~140 °C). During sustained overload, the device cycles between regulation and shutdown-limiting average power dissipation. This protects against permanent damage but causes output voltage interruption; design must ensure adequate copper area and airflow to keep R_thJA ≤ 200 °C/W (SOT23-5L value) under worst-case load.