STMicroelectronics LK112M80TR

Overview

LK112M80TR from STMicroelectronics is an 8.0 V fixed-output, 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 quiescent current as low as 0.1 µA in OFF mode. It operates from input voltages as low as V_OUT + 0.5 V (i.e., 8.5 V minimum) up to 14 V and is used in battery-powered instrumentation requiring stable, ultra-low-noise bias rails.

For engineers reviewing the LK112M80TR datasheet, LK112M80TR pinout, LK112M80TR application, or LK112M80TR equivalent, key selection criteria include dropout voltage at 150 mA, shutdown logic threshold (0.6 V max for OFF), bypass capacitor dependency for noise reduction, thermal shutdown behavior (150 °C junction limit), and SOT23-5L package thermal resistance (R_thJA = 255 °C/W).

Technical Context

The LK112M80TR 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 directly controls the internal electronic switch, disabling regulation and reducing I_q to sub-100 nA.

Internal protection includes foldback current limiting, thermal shutdown at ~150 °C, and short-circuit detection that forces automatic shutdown. Output voltage accuracy is ±2% over load, line, and temperature, with temperature coefficient of 0.09 mV/°C and supply voltage rejection of 55 dB at 400 Hz.

Key Specifications

Pinout & Package

Supplied in SOT23-5L package: 5-pin surface-mount, 1.3 mm height, R_thJA = 255 °C/W, R_thJC = 81 °C/W. Exposed die attach flag internally connected to GND for improved thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV70780DQNR and MCP1703T-8002E/MB, the LK112M80TR uniquely combines ultra-low OFF-mode current (0.1 µA), dedicated noise-reduction bypass pin, and 350 mV dropout in SOT23-5L - making it optimal for long-life, noise-critical, space-constrained battery systems.

Availability

LK112M80TR is available at Aetrix Electronics and suitable for portable medical sensors, industrial process transmitters, and wireless sensor node MCU supply requiring stable component supply, consistent parametric performance, and long-term manufacturability assurance.

Supply support for LK112M80TR 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 battery-operated and space-constrained instrumentation systems.

FAQ

What is the minimum input voltage required for LK112M80TR to regulate 8.0 V output?

The LK112M80TR requires input voltage ≥ V_OUT + 0.5 V = 8.5 V for proper regulation, per datasheet Section 3. This reflects its PNP-based architecture and 350 mV maximum dropout at 150 mA. Operation below 8.5 V results in unregulated output or dropout behavior.

Can the BYPASS pin be left floating or tied directly to OUT?

No. The BYPASS pin must be connected to a 0.1 µF ceramic capacitor to GND to achieve the specified 30 µV_rms noise performance. Leaving it floating or tying it to OUT disables the internal noise-reduction path and degrades output noise to unspecified levels - confirmed in Section 4 "Description" and Figure 22 (Noise spectrum).

Does LK112M80TR require an input capacitor, and what value is recommended?

Yes. A minimum 1 µF ceramic capacitor is required between IN and GND, placed as close as possible to the device. This stabilizes the input impedance and suppresses high-frequency noise from upstream sources, as specified in Section 4 "Electrical characteristics" test conditions and validated in Figure 21 (Stability).

How does thermal shutdown behave during sustained overload?

When junction temperature reaches ~150 °C, the internal thermal shutdown circuit disables the pass transistor, dropping output voltage to near zero. After cooldown below hysteresis threshold (~135 °C), regulation automatically resumes - no manual reset required. This behavior is documented in Section 4 and verified in Figure 8 (Short-circuit current vs. dropout voltage).