STMicroelectronics LK112M38TR

Overview

LK112M38TR 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 with 350 mV dropout at full load, 30 µVrms output noise (10 Hz–80 kHz), and 250 µA max quiescent current in ON mode. Designed for precision power rails in battery-powered instrumentation and sensor interfaces, it supports 3.8 V fixed output with input range from 4.3 V to 14 V.

For engineers reviewing the LK112M38TR datasheet, LK112M38TR pinout, LK112M38TR application, or LK112M38TR equivalent, key selection criteria include ultra-low noise performance, sub-100 nA shutdown current, SOT23-5L footprint compatibility, and thermal/overcurrent protection integration - critical for space-constrained, low-power analog signal chains.

Technical Context

The LK112M38TR implements a PNP-based LDO architecture enabling low dropout while maintaining stability with minimal external capacitance (2.2 µF output, 0.1 µF bypass). Its TTL/CMOS-compatible SHDN pin enables precise system-level power sequencing with <0.6 V logic-low threshold and 1.8 V logic-high activation level.

Internal protection includes thermal shutdown (150 °C junction limit), short-circuit current limiting, and reverse-current blocking. Noise reduction is achieved via dedicated Bypass pin accepting 0.1 µF capacitor to suppress broadband output ripple to 30 µVrms at 60 mA load.

Key Specifications

Pinout & Package

Supplied in compact SOT23-5L package (2.95 mm × 1.60 mm × 1.30 mm), optimized for thermal performance via internal die attach flag connection to GND pin.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6219B382MR-G and ADP125ARHZ-3.8-R7, the LK112M38TR uniquely balances ultra-low noise (30 µVrms), sub-100 nA shutdown, and integrated thermal/overcurrent protection in the smallest SOT23-5L footprint - making it optimal for miniaturized, battery-critical analog systems where reliability and noise performance are non-negotiable.

Availability

LK112M38TR is available at Aetrix Electronics and suitable for portable medical sensors, industrial process transmitters, and wireless sensor nodes requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.

Supply support for LK112M38TR 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The LK112 series belongs to ST's precision linear regulator product line, engineered specifically for ultra-low-noise, low-quiescent-current power management in battery-powered and signal-integrity-critical applications.

FAQ

What is the minimum input voltage required for stable 3.8 V output?

The LK112M38TR requires input voltage ≥ V_OUT + 0.5 V = 4.3 V for stable regulation. Below this, dropout occurs and output voltage drops linearly with input. The device remains functional down to 2.5 V input but cannot maintain 3.8 V output below 4.3 V.

Can the Bypass pin be left unconnected?

No - leaving the Bypass pin floating degrades noise performance. A 0.1 µF ceramic capacitor must be placed between Bypass and GND to achieve the specified 30 µVrms output noise. Omission increases noise to ~120 µVrms per typical characteristics data.

Does the LK112M38TR support reverse-voltage protection?

No - the device lacks integrated reverse-voltage protection. Applying reverse polarity to IN or OUT can cause permanent damage. External protection (e.g., series Schottky diode on IN) is required if system-level reverse voltage exposure is possible.

How does thermal shutdown behave during overload?

Under sustained overcurrent or high ambient temperature, the internal thermal circuit triggers at ~150 °C junction temperature, disabling output until junction cools by ~20 °C. Recovery is automatic and does not require cycling SHDN; hysteresis prevents oscillation during thermal recovery.