STMicroelectronics LK112SM80TR

Overview

LK112SM80TR from STMicroelectronics is a low-noise, low-dropout linear voltage regulator with shutdown control, designed for precision power management in space-constrained applications. It delivers up to 200 mA output current, maintains ≤500 mV dropout at full load, achieves ±2% output voltage accuracy at 25 °C, and features ultra-low 0.1 µA quiescent current in OFF mode. It is used in battery-powered sensor nodes requiring stable 3.3 V rail generation with minimal thermal dissipation.

For engineers reviewing the LK112SM80TR datasheet, LK112SM80TR pinout, LK112SM80TR application, or LK112SM80TR equivalent, key selection criteria include its SOT23-5L package footprint, TTL/CMOS-compatible SHDN logic interface, 30 µV_rms output noise (10 Hz–80 kHz), internal thermal and short-circuit protection, and input voltage range of V_OUT + 0.5 V to 14 V.

Technical Context

The LK112SM80TR integrates an internal PNP pass transistor to achieve low dropout while maintaining high PSRR (55 dB at 400 Hz) and tight line/load regulation (≤40 mV and ≤90 mV respectively). Its shutdown function reduces I_Q to 100 nA max and enables fast wake-up via TTL/CMOS-level control on Pin 1 (SHDN).

Output noise is actively suppressed using an external 0.1 µF capacitor on the Bypass pin, reducing broadband thermal noise to 30 µV_rms. Internal current limiting and thermal shutdown (T_J < 150 °C) ensure robust operation under fault conditions without external components.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 1.3 mm height, 2.95 mm × 1.60 mm footprint, ECOPACK® compliant, with exposed die attach flag for enhanced thermal performance (R_thJA = 255 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2112K-3.3TRG1 and MCP1703T-3302E/MB, the LK112SM80TR uniquely combines ultra-low OFF-mode I_Q, a dedicated bypass pin for noise control, and integrated thermal/overcurrent protection - making it optimal for battery-powered precision analog systems where reliability and runtime are co-prioritized.

Availability

LK112SM80TR is available at Aetrix Electronics and suitable for wearable health monitors, industrial sensor nodes, smart meter RF modules, and portable medical diagnostic devices requiring stable component supply and long-term manufacturability.

Supply support for LK112SM80TR 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, sensors, and analog components for industrial, automotive, and consumer markets.

The LK112S series targets ultra-low-power, noise-sensitive applications in portable and battery-operated equipment, emphasizing minimal quiescent current, precise output regulation, and integrated protection features in compact packages.

FAQ

What is the minimum input voltage required for LK112SM80TR to regulate 3.3 V output?

The LK112SM80TR requires a minimum input voltage of V_OUT + 0.5 V = 3.8 V for proper regulation at 3.3 V output. This is specified in the datasheet for versions with V_OUT > 2 V. Below this threshold, dropout behavior occurs and output voltage drops linearly with input.

Can the Bypass pin be left unconnected?

No - leaving the Bypass pin floating degrades output noise performance. The datasheet specifies a 0.1 µF ceramic capacitor must be connected between Bypass and GND to achieve the rated 30 µV_rms noise. Omitting it results in typical noise rising to ~100 µV_rms.

Does LK112SM80TR support reverse polarity protection?

No - the device lacks built-in reverse-voltage protection. Applying reverse polarity to the IN or OUT pins may cause irreversible damage. External protection (e.g., series diode or MOSFET-based circuit) is required if reverse input is possible in the target application.

How does thermal shutdown behave during sustained overload?

Under sustained overcurrent or high ambient temperature, the internal thermal shutdown circuit disables the pass transistor when junction temperature exceeds ~150 °C. The device remains latched OFF until T_J falls below the hysteresis threshold (~135 °C), then automatically resumes regulation without external intervention.