STMicroelectronics LK112M27TR

Overview

LK112M27TR 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 0.1 µA quiescent current in OFF mode. It operates from input voltages as low as VOUT + 0.5 V (for VOUT > 2 V) and supports 2.7 V fixed output voltage in SOT23-5L package for power-sensitive sensor and portable microcontroller applications.

For engineers reviewing the LK112M27TR datasheet, LK112M27TR pinout, LK112M27TR application, or LK112M27TR equivalent, key selection criteria include ultra-low quiescent current in shutdown, noise-bypass capability via dedicated Bypass pin, thermal/overcurrent protection, and TTL/CMOS-compatible enable logic - critical for battery-powered IoT nodes and precision analog subsystems.

Technical Context

The LK112M27TR implements a PNP-based LDO architecture enabling low dropout while maintaining stability with minimal external capacitance (CI = 1 µF, CO = 2.2 µF). Its shutdown function accepts logic-level inputs (ON ≥ 1.8 V, OFF ≤ 0.6 V), reducing I_Q to < 0.1 µA and isolating output during sleep states.

Noise performance is enhanced by an internal bypass path routed to the dedicated Bypass pin, where a 0.1 µF capacitor reduces output noise to 30 µV_rms. Internal thermal shutdown (T_J < 150 °C) and current limiting (150 mA) provide fault resilience without external circuitry.

Key Specifications

Pinout & Package

The LK112M27TR is housed in a thermally enhanced SOT23-5L package with exposed die attach flag connected internally to GND, achieving R_thJA = 255 °C/W and 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 TPS78027DRVR and MCP1702T-2702E/MB, the LK112M27TR uniquely balances ultra-low OFF-mode current, dedicated noise-bypass capability, and robust thermal/overcurrent protection - making it optimal for battery-powered precision analog systems requiring both longevity and signal integrity.

Availability

LK112M27TR is available at Aetrix Electronics and suitable for wearable health monitors, industrial 4–20 mA transmitters, wireless sensor modules, and portable medical diagnostics requiring stable component supply and long-term lifecycle support.

Supply support for LK112M27TR 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 high-performance linear regulator product line, engineered specifically for ultra-low-noise, low-quiescent-current power delivery in space-constrained, battery-operated applications demanding precision analog performance.

FAQ

What is the minimum input voltage required for regulation at 2.7 V output?

The LK112M27TR requires a minimum input voltage of V_OUT + 0.5 V = 3.2 V for stable regulation, per the datasheet's operative input range specification for V_OUT > 2 V. Below this threshold, dropout behavior begins and output voltage drops linearly with input.

Can the Bypass pin be left unconnected?

Yes, the Bypass pin may be left floating or unconnected, but doing so results in higher output noise (typ. 80 µV_rms). To achieve the specified 30 µV_rms, a 0.1 µF ceramic capacitor must be placed between Bypass and GND, as confirmed in Section 4 Electrical Characteristics and Figure 22 (Noise spectrum).

Does the LK112M27TR require an input capacitor?

Yes, a minimum 1 µF ceramic input capacitor (CI) is required for stability and transient response, as specified in all electrical test conditions (e.g., Table 5, footnote). Omitting CI risks oscillation and degraded line transient performance, particularly under fast input voltage steps.

Is the shutdown function compatible with 1.8 V GPIO from modern MCUs?

Yes - the SHDN pin recognizes logic high at ≥1.8 V and logic low at ≤0.6 V, matching standard 1.8 V CMOS output levels. The shutdown input current is only 12–35 µA at V_SHDN = 1.8 V, imposing negligible load on MCU GPIO drivers.