STMicroelectronics LK112M13TR

Overview

LK112M13TR from STMicroelectronics is a low-noise, low-dropout linear voltage regulator with integrated shutdown control and internal PNP pass transistor. It delivers up to 150 mA output current, maintains 350 mV dropout at full load, achieves 30 µV_rms output noise (10 Hz–80 kHz), and supports 1.3 V fixed output voltage in SOT23-5L package - ideal for powering precision analog sensors and low-power microcontrollers in battery-operated IoT edge nodes.

For engineers reviewing the LK112M13TR datasheet, LK112M13TR pinout, LK112M13TR application, or LK112M13TR equivalent, key selection criteria include ultra-low quiescent current (0.1 µA in OFF mode), noise-bypass pin capability, thermal/overcurrent protection, and input voltage compatibility down to V_OUT + 0.5 V for V_OUT > 2 V - critical for energy-constrained portable designs.

Technical Context

The LK112M13TR implements a PNP-based LDO architecture enabling low dropout while maintaining stability with minimal external capacitance (1 µF input, 2.2 µF output). Its TTL/CMOS-compatible SHDN pin controls an internal electronic switch, reducing quiescent current below 100 nA in shutdown.

Output noise is actively suppressed via a dedicated Bypass pin accepting a 0.1 µF capacitor, lowering RMS noise to 30 µV_rms. Internal protection includes thermal shutdown (T_J < 150 °C), current limiting, and short-circuit foldback - all operating without external components.

Key Specifications

Pinout & Package

SOT23-5L surface-mount package with exposed die attach flag for enhanced thermal dissipation (R_thJA = 255 °C/W, R_thJC = 81 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2210K-13TRG1 and TPS7A0513PDBVR, the LK112M13TR uniquely balances ultra-low noise (30 µV_rms with bypass), sub-µA shutdown, and 350 mV dropout - making it optimal where analog integrity and battery longevity coexist under tight PCB area constraints.

Availability

LK112M13TR is available at Aetrix Electronics and suitable for wearable health monitors, industrial wireless transmitters, smart meter auxiliary rails, and medical point-of-care diagnostic modules requiring stable component supply with guaranteed long-term manufacturability.

Supply support for LK112M13TR 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 LK112 series belongs to ST's precision analog LDO portfolio, engineered specifically for ultra-low-noise, low-quiescent-current regulation in space-constrained, battery-powered applications demanding high PSRR and thermal robustness.

FAQ

What is the minimum input voltage required for LK112M13TR to regulate 1.3 V output?

The LK112M13TR requires a minimum input voltage of 2.5 V, as specified for versions with V_OUT < 2 V. This is due to internal headroom constraints of the PNP pass transistor and control circuitry - not the theoretical dropout limit. Operating below 2.5 V risks loss of regulation even if V_IN − V_OUT > 350 mV.

Can the Bypass pin be left unconnected?

Yes, the Bypass pin may be left floating or tied to GND if ultra-low noise is not required. However, doing so results in typical output noise of ~120 µV_rms (vs. 30 µV_rms with 0.1 µF). No instability or reliability impact occurs - the pin is internally high-impedance and only affects noise performance.

Does LK112M13TR support reverse polarity protection?

No, the LK112M13TR lacks built-in reverse-polarity protection. Applying negative voltage to IN or positive voltage to GND exceeds absolute maximum ratings (V_I = −0.3 V min) and may cause permanent damage. External protection diodes or MOSFET-based circuits are required for reverse-voltage resilience.

How does thermal shutdown behave during sustained overload?

Under sustained output short-circuit, the LK112M13TR enters thermal shutdown when junction temperature exceeds 150 °C, disabling output. It remains latched off until T_J drops below ~135 °C (typical hysteresis), then automatically resumes regulation - no external reset is needed. This cycle repeats to limit average power dissipation and prevent package damage.