STMicroelectronics LK112SM15TR

Overview

LK112SM15TR from STMicroelectronics is a low-noise, low-dropout linear voltage regulator with integrated shutdown control and 1.5 V fixed output. It delivers up to 200 mA, maintains ±2% output accuracy at 25 °C, achieves 500 mV max dropout at full load, and operates from input voltages as low as V_OUT + 0.5 V (i.e., 2.0 V min). It is used in battery-powered sensor nodes and portable instrumentation requiring stable, ultra-low-noise bias.

For engineers reviewing the LK112SM15TR datasheet, LK112SM15TR pinout, LK112SM15TR application, or LK112SM15TR equivalent, key selection criteria include its 0.1 µA OFF-mode quiescent current, 30 µV_rms output noise (10 Hz–80 kHz), SOT23-5L package thermal performance (R_thJA = 255 °C/W), and TTL/CMOS-compatible SHDN logic interface.

Technical Context

The LK112SM15TR employs an internal PNP pass transistor to achieve low dropout and high PSRR (55 dB at 400 Hz). Its shutdown function accepts logic-level inputs (ON ≥1.8 V, OFF ≤0.6 V), reducing quiescent current to ≤0.1 µA in OFF mode while maintaining internal thermal and short-circuit protection.

Output noise is actively suppressed via an external 0.1 µF capacitor on the Bypass pin, enabling 30 µV_rms performance under 60 mA load. Line regulation stays within 0.7–20 mV across VI = V_OUT+1 V to V_OUT+6 V, and load regulation remains ≤90 mV from 1–200 mA.

Key Specifications

Pinout & Package

SOT23-5L package: compact 2.95 mm × 1.60 mm surface-mount outline with exposed die attach flag for enhanced thermal dissipation (R_thJC = 81 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A0515PDBVR and MCP1703T-1502E/MB, the LK112SM15TR uniquely balances ultra-low OFF current, industry-leading 30 µV_rms noise, and integrated bypass functionality - making it optimal for compact, battery-powered analog-sensing systems where both longevity and signal fidelity are critical.

Availability

LK112SM15TR is available at Aetrix Electronics and suitable for wearable health monitors, industrial sensor nodes, portable gas detectors, and smart meter auxiliary rails requiring stable component supply across long-lifecycle deployments.

Supply support for LK112SM15TR 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, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

The LK112S series was developed specifically for ultra-low-power, low-noise analog and mixed-signal applications in battery-constrained edge devices - emphasizing precision regulation, minimal quiescent draw, and robust thermal behavior in miniature packages.

FAQ

What is the minimum input voltage required for regulation at 1.5 V output?

The LK112SM15TR requires a minimum input voltage of 2.0 V (V_OUT + 0.5 V) for regulation. This is specified for all versions with V_OUT ≤ 2 V. Below 2.0 V input, the device enters dropout and output voltage drops linearly with input.

Can the Bypass pin be left unconnected?

No. Leaving the Bypass pin floating degrades output noise performance. A 0.1 µF ceramic capacitor must be placed between Bypass and GND to achieve the specified 30 µV_rms noise. Omitting this capacitor increases noise to typical values above 100 µV_rms.

Does the LK112SM15TR support reverse polarity protection?

No. The device lacks internal reverse-voltage protection. Applying reverse polarity to the IN or OUT pins may cause permanent damage. External protection diodes or MOSFET-based circuits must be added if reverse input is possible in the application.

How does thermal performance change with PCB copper area?

R_thJA is rated at 255 °C/W for the standard JEDEC 2-layer board. Adding ≥100 mm² of 2-oz copper connected to the GND pin reduces R_thJA by ~35 °C/W. The exposed die attach flag must be soldered directly to this copper pour to realize the improvement.