STMicroelectronics LK112M50TR

Overview

LK112M50TR from STMicroelectronics is a 5.0 V, 150 mA low-dropout linear regulator with integrated shutdown control and ultra-low noise (30 µV_rms, 10 Hz–80 kHz) for precision analog and battery-powered systems. It features 350 mV dropout at full load, 250 µA max quiescent current in ON mode, and 0.1 µA in OFF mode, housed in an SOT23-5L package.

For engineers reviewing the LK112M50TR datasheet, LK112M50TR pinout, LK112M50TR application, or LK112M50TR equivalent, key selection criteria include output noise performance, shutdown leakage, thermal shutdown behavior, dropout voltage vs. load, and bypass capacitor dependency for noise reduction.

Technical Context

The LK112M50TR uses an internal PNP pass transistor to achieve low dropout and stable regulation across input voltages from 5.5 V to 14 V (V_OUT = 5.0 V). Its TTL/CMOS-compatible SHDN pin enables logic-level on/off control with <0.1 µA shutdown current.

It integrates overcurrent and thermal protection, shutting down when junction temperature exceeds 150 °C or output current exceeds 150 mA. Output noise is reduced via external 0.1 µF capacitor on the Bypass pin, enabling sub-35 µV_rms performance in sensitive signal chains.

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 TLV70750DBVR and MCP1703T-5002E/MB, the LK112M50TR uniquely combines sub-µA shutdown, dedicated noise-bypass capability, and robust thermal/current protection - making it optimal for battery-constrained, noise-sensitive, and field-deployed systems requiring reliability under fault conditions.

Availability

LK112M50TR is available at Aetrix Electronics and suitable for portable medical sensors, industrial data acquisition systems, wireless sensor nodes, and automotive body control modules requiring stable component supply with guaranteed long-term availability.

Supply support for LK112M50TR 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 LK112 series belongs to ST's precision low-noise LDO portfolio, engineered specifically for battery-powered instrumentation, portable diagnostics, and signal-chain power delivery where noise, quiescent current, and reliability under fault are primary design constraints.

FAQ

What is the minimum input voltage required for stable 5.0 V output?

The LK112M50TR requires a minimum input voltage of 5.5 V (V_OUT + 0.5 V) for stable regulation at full 150 mA load. At lighter loads, it can operate down to 5.2 V, but dropout voltage increases nonlinearly below rated current - design margin should maintain ≥5.5 V under worst-case temperature and load conditions.

Can the Bypass pin be left unconnected?

No - leaving the Bypass pin floating degrades output noise performance to >100 µV_rms. A 0.1 µF X7R ceramic capacitor must be placed between Bypass and GND, located within 2 mm of the pin, to achieve the specified 30 µV_rms noise. No series resistor or ferrite bead is permitted on this node.

Does the SHDN pin require a pull-up resistor?

No external pull-up is required. The SHDN pin has internal logic-level compatibility and draws only 35 µA max when asserted high. It may be driven directly from a GPIO or open-drain controller output; however, a 100 kΩ pull-down is recommended if left unconnected to ensure default OFF state during power-up.

How does thermal shutdown behave during sustained overload?

When junction temperature reaches 150 °C, the LK112M50TR disables the pass transistor and holds output at 0 V until temperature falls below ~135 °C (typical hysteresis), then automatically resumes regulation. This cycle repeats continuously under constant overload - no latch or manual reset is needed, and the device survives repeated thermal cycling per JEDEC JESD22-A104.