STMicroelectronics LDLN025PU18R

Overview

LDLN025PU18R from STMicroelectronics is a 250 mA ultra-low-noise low-dropout (LDO) voltage regulator with 1.8 V fixed output, designed for noise-sensitive analog and RF circuitry. It operates from 1.5 V to 5.5 V input, delivers 6.5 µV_RMS output noise (10 Hz–100 kHz), achieves 120 mV dropout at 250 mA, and draws only 12 µA quiescent current at no load-enabling extended battery life in portable image sensors and VCO power rails.

For engineers reviewing the LDLN025PU18R datasheet, LDLN025PU18R pinout, LDLN025PU18R application, or LDLN025PU18R equivalent, this LDO is selected for precision biasing of ADC references, RF front-end ICs, and high-resolution camera modules where PSRR >60 dB at 100 kHz and ±2% output accuracy across –40 °C to +125 °C are critical.

Technical Context

The LDLN025PU18R employs a bandgap-referenced error amplifier with internal soft-start and logic-controlled enable to manage inrush and shutdown sequencing. Its architecture maintains stable regulation under dynamic load transients (±40 mV deviation at 1 mA→250 mA step) while sustaining >80 dB PSRR at 100 Hz and >60 dB at 100 kHz.

Thermal protection triggers at 160 °C with 20 °C hysteresis, and overcurrent limiting caps short-circuit current between 250 mA and 500 mA. The device is internally compensated for stability with 0.7–1 µF ceramic output capacitors and supports output discharge via 230 Ω internal pull-down when disabled.

Key Specifications

Pinout & Package

LDLN025PU18R is packaged in DFN4-1x1 (1.0 mm × 1.0 mm, 0.38 mm height, 0.65 mm pitch), featuring an exposed thermal pad that must be connected to GND for optimal thermal performance (R_thJA = 220 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B182MR-G and ADP160AUJZ-1.8-R7, LDLN025PU18R uniquely combines 250 mA drive, 6.5 µV_RMS noise, and integrated output discharge-making it the only option qualified for next-generation smartphone image sensor and 5G mmWave VCO applications demanding simultaneous high current, ultra-low noise, and rapid rail collapse.

Availability

LDLN025PU18R is available at Aetrix Electronics and suitable for smartphone camera modules, RF transceiver power supplies, portable instrumentation ADCs, and industrial IoT sensor nodes requiring stable component supply with guaranteed long-term lifecycle support.

Supply support for LDLN025PU18R 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, delivering silicon solutions for automotive, industrial, and consumer markets with emphasis on energy efficiency and reliability.

LDLN025PU18R belongs to ST's ultra-low-noise LDO family, engineered specifically for powering noise-sensitive analog and RF circuits-including image sensors, VCOs, and high-resolution data converters-in space-constrained, battery-powered devices.

FAQ

What is the recommended input and output capacitor configuration for LDLN025PU18R?

Use a 1 µF X7R ceramic capacitor on both input (C_IN) and output (C_OUT). The device is stable with C_OUT values from 0.7 µF to 10 µF and ESR between 5 mΩ and 500 mΩ. Avoid tantalum or aluminum electrolytic capacitors due to ESR and aging effects that compromise transient response and noise performance.

Does LDLN025PU18R require an external pull-up resistor on the EN pin?

No. The EN pin has an internal 1 MΩ pull-down resistor, so it defaults to OFF when left unconnected. A logic-high signal ≥1.2 V (e.g., from a microcontroller GPIO) is required to enable regulation. No external pull-up is needed unless system-level fail-safe behavior mandates default-ON operation.

How does thermal performance differ among the DFN4-1x1, Flip-Chip4, and SOT23-5L packages?

DFN4-1x1 has R_thJA = 220 °C/W, Flip-Chip4 = 210 °C/W, and SOT23-5L = 200 °C/W. While SOT23-5L offers the lowest junction-to-ambient resistance, its larger footprint (2.95 mm × 1.60 mm) conflicts with ultra-compact layouts. DFN4-1x1 provides the best area efficiency (1.0 mm²) and sufficient thermal margin for 250 mA continuous operation with proper PCB copper pour.

Can LDLN025PU18R be used with a 5 V input to regulate 1.8 V at 250 mA?

Yes. With a 5 V input, the dropout voltage is 120 mV typical (250 mV max), resulting in 3.7 V of headroom-well within the absolute maximum rating of 7 V input. Power dissipation will be (5 V − 1.8 V) × 0.25 A = 0.8 W, requiring adequate PCB copper area and airflow or derating above 85 °C ambient per the thermal data in DS11756 Rev 8, page 5.