STMicroelectronics LDK120M18R

Overview

LDK120M18R from STMicroelectronics is a 200 mA, 1.8 V fixed-output low-dropout (LDO) regulator with 100 mV typical dropout at 100 mA, 100 µA max quiescent current, ±2.0% output voltage tolerance at 25 °C, and operation from 1.9 V to 5.5 V input. It delivers ultra-low noise (51 µVRMS, 10 Hz–100 kHz, with 10 nF bypass capacitor) and supports logic-controlled shutdown (<1 µA OFF-mode current), making it ideal for powering RF sections and precision analog circuitry in portable battery-powered devices.

For engineers reviewing the LDK120M18R datasheet, LDK120M18R pinout, LDK120M18R application, or LDK120M18R equivalent, key selection criteria include dropout performance under 200 mA load, ceramic-capacitor stability (1 µF COUT), thermal shutdown behavior (160 °C), EN pin logic thresholds (0.4 V low / 1.2 V high), and noise-sensitive use in camera image sensors or Bluetooth baseband ICs.

Technical Context

The LDK120M18R employs a PMOS pass transistor architecture enabling near-zero gate-drive voltage requirements and stable operation down to 1.9 V input-critical for single-cell Li-ion and Li-polymer systems. Its internal bandgap reference and error amplifier deliver tight DC accuracy (±2.0% at 25 °C) and low line/load regulation (0.05 %/V and 0.006 %/mA).

It integrates active current limiting (400 mA short-circuit current), thermal foldback protection (160 °C shutdown with 20 °C hysteresis), and EN-controlled fast startup (<100 µs). The device is optimized for ceramic output capacitors only-no ESR requirement-and supports optional 10 nF bypass capacitor on BYP pin to reduce output noise by >65%.

Key Specifications

Pinout & Package

LDK120M18R is packaged in SOT23-5L (JEDEC TO-236AB), a 5-pin surface-mount package measuring 2.95 mm × 1.60 mm × 1.45 mm with 0.95 mm lead pitch. It features gull-wing leads, RoHS-compliant matte-tin plating, and ECOPACK2 environmental compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6219B182MR-G and RT9013-18GB, the LDK120M18R uniquely balances ultra-low noise (51 µVRMS), sub-1 µA shutdown, and robust protection-making it the optimal choice for battery-constrained, noise-critical mixed-signal systems requiring guaranteed 200 mA at minimal dropout.

Availability

LDK120M18R is available at Aetrix Electronics and suitable for mobile camera modules, Bluetooth LE audio devices, industrial handheld scanners, and wearable health monitors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LDK120M18R 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 LDK120 series belongs to ST's precision analog LDO portfolio, engineered specifically for ultra-low-noise, low-IQ power management in portable and battery-operated equipment where efficiency, size, and signal integrity are critical.

FAQ

What is the minimum input voltage required for stable 1.8 V output at 200 mA?

The LDK120M18R maintains regulation down to an input voltage of 1.9 V. At 200 mA load, its maximum dropout is 300 mV (per datasheet Table 4), so minimum functional VIN = 1.8 V + 0.3 V = 2.1 V. Below that, output voltage drops linearly with input.

Can the BYP pin be left unconnected if noise performance is not critical?

Yes. For the fixed-output LDK120M18R, the BYP pin is optional: if unused, it must be left floating with no PCB routing or solder mask opening. Leaving it unconnected results in 148 µVRMS output noise instead of 51 µVRMS-but full regulation, stability, and all other specifications remain unaffected.

Is a minimum output capacitor required, and what type is recommended?

Yes: a minimum 1 µF X5R or X7R ceramic capacitor is mandatory at the OUT pin for stability. Tantalum or electrolytic capacitors are not supported. The device is optimized for low-ESR ceramics and exhibits no oscillation or phase margin degradation with values from 1 µF to 22 µF.

Does the LDK120M18R support reverse current blocking during shutdown?

No. The LDK120M18R does not integrate reverse current blocking. When EN = low and VIN > VOUT, reverse current can flow from OUT to IN through the internal PMOS body diode. To prevent this, an external Schottky diode in series with the IN rail or a dedicated reverse-blocking LDO (e.g., ST's LD5610) must be used.