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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

STMicroelectronics LK112M28TR

Name: LK112M28TR
Brand: STMicroelectronics
SKU: LK112M28TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LK112M28TR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Package:: SC-74A, SOT-753

Datasheet:: LK112M28TR.pdf

Description:: IC REG LINEAR 2.8V 150MA SOT23-5

Quantity:: RFQ Add To RFQ list

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Inventory:2,206

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Product details

Overview

LK112M28TR from STMicroelectronics is a low-noise, low-dropout linear voltage regulator with integrated shutdown control and 2.8 V fixed output. It delivers up to 150 mA, maintains dropout voltage of 350 mV at full load, achieves 30 µVrms output noise (10 Hz–80 kHz), and draws only 250 µA quiescent current in ON mode. It is used in battery-powered sensor nodes requiring stable, ultra-low-noise supply rails.

For engineers reviewing the LK112M28TR datasheet, LK112M28TR pinout, LK112M28TR application, or LK112M28TR equivalent, key selection criteria include its 2.8 V fixed output, SOT23-5L package footprint, TTL/CMOS-compatible SHDN pin, 0.1 µF bypass capacitor requirement for noise reduction, and thermal/current protection features.

Technical Context

The LK112M28TR integrates an internal PNP pass transistor enabling low-dropout operation down to 290 mV at 150 mA. Its shutdown function accepts logic-level inputs (ON ≥1.8 V, OFF ≤0.6 V) and reduces quiescent current to 0.1 µA, making it suitable for intermittent-power systems.

Output noise is actively suppressed via a dedicated Bypass pin accepting a 0.1 µF capacitor, reducing RMS noise to 30 µV across 10 Hz–80 kHz. Internal thermal shutdown (150 °C limit) and foldback current limiting protect against overtemperature and short-circuit faults.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 2.8 V ±2 % - ensures precise biasing for 2.8 V logic or analog circuitry without external feedback.
Max Output Current	150 mA - supports moderate-power microcontrollers, RF transceivers, or precision ADCs.
Dropout Voltage	350 mV at 150 mA - enables regulation from 3.15 V input, critical for single-cell Li-ion or alkaline battery systems.
Quiescent Current	250 µA (ON), 0.1 µA (OFF) - extends battery life in always-on sensing and wake-on-event architectures.
Output Noise	30 µV_rms (10 Hz–80 kHz, 0.1 µF bypass) - meets low-noise requirements for audio codecs, precision op-amps, and RF LDO stages.
Input Voltage Range	3.3 V to 14 V - accommodates wide-input industrial supplies while maintaining regulation above V_OUT + 0.5 V.
Thermal Shutdown	150 °C junction limit - prevents damage during sustained overload or poor PCB thermal design.

Pinout & Package

Package: SOT23-5L - compact 5-pin surface-mount package with exposed die attach flag for enhanced thermal dissipation (R_thJA = 255 °C/W).

Pin/Terminal	Circuit Role	Design Meaning
1 (SHDN)	Shutdown control input	Active-high TTL/CMOS-compatible enable; pulls below 0.6 V to disable regulator and reduce I_q to 0.1 µA.
2 (GND)	Ground reference	Internally connected to die attach flag - improves thermal resistance and power handling capability.
3 (BYPASS)	Noise reduction node	Accepts 0.1 µF capacitor to shunt high-frequency noise and achieve 30 µV_rms output noise performance.
4 (OUT)	Regulated output	Delivers stable 2.8 V ±2 % to load; requires 2.2 µF ceramic output capacitor for stability.
5 (IN)	Unregulated input	Accepts 3.3–14 V DC; must exceed V_OUT + 0.5 V for proper regulation under all operating conditions.

Key Features

Feature	Design Value
Low-noise architecture	30 µV_rms output noise with 0.1 µF bypass capacitor - eliminates need for secondary filtering in sensitive analog signal chains.
Ultra-low quiescent current	0.1 µA in shutdown mode - enables multi-year operation on coin-cell batteries in IoT endpoint devices.
Integrated protection	Thermal shutdown + current limiting - prevents latch-up or destruction during output short or ambient temperature rise.
Logic-compatible enable	SHDN pin accepts 1.8 V logic high - simplifies direct interfacing with 1.8 V/3.3 V microcontroller GPIO without level-shifting.
Wide input range	Operates from V_OUT + 0.5 V up to 14 V - supports flexible input sourcing including buck-boost pre-regulators or unregulated wall adapters.

Applications

Wireless Sensor Node Power

Portable Medical Monitor

Use Scenario: Battery-powered environmental sensor transmitting data via BLE or LoRaWAN.

IC Role / Device Role / Timing Role: Primary 2.8 V LDO supplying MCU, radio, and analog front-end.

Use Value: 30 µV_rms noise ensures clean ADC reference and RF synthesizer VCO supply, minimizing measurement drift and phase noise.

Use Scenario: Handheld ECG or pulse oximeter with continuous analog signal acquisition.

IC Role / Device Role / Timing Role: Low-noise 2.8 V rail for instrumentation amplifier and 16-bit sigma-delta ADC.

Use Value: Ultra-low dropout (350 mV) extends usable battery life by enabling operation down to 3.15 V input from two alkaline cells.

Industrial PLC I/O Module

Smart Meter Analog Front-End

Use Scenario: DIN-rail mounted sensor interface module powered from 12 V DC bus.

IC Role / Device Role / Timing Role: Local 2.8 V regulator for isolated digital isolators and RS-485 transceivers.

Use Value: 150 mA output current and thermal shutdown ensure reliable operation in enclosed enclosures with limited airflow.

Use Scenario: Revenue-grade electricity meter requiring metrology-grade analog conditioning.

IC Role / Device Role / Timing Role: Precision 2.8 V supply for anti-aliasing filters and reference buffers.

Use Value: ±2 % output tolerance and <0.1 mV/°C tempco maintain accuracy across –40 °C to +85 °C operating range.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Torex XC6219B282MR-G	2.8 V fixed, 150 mA, 250 mV dropout, 40 µV_rms noise, SOT23-5	Higher noise floor; no dedicated bypass pin - requires larger output cap for noise suppression	Select when lower cost is prioritized and 40 µV_rms noise is acceptable.
Diodes Inc. AP2202K-2.8TRG1	2.8 V fixed, 150 mA, 600 mV dropout, 120 µV_rms noise, SOT23-5	Higher dropout and noise; lacks thermal shutdown	Use only in non-critical, low-ambient-temperature applications with ample headroom.

Compared with XC6219B282MR-G and AP2202K-2.8TRG1, the LK112M28TR uniquely combines 30 µV_rms noise, 350 mV dropout, and integrated thermal/current protection - making it optimal for space-constrained, battery-operated, and metrology-grade designs where reliability and signal integrity are co-prioritized.

Availability

LK112M28TR is available at Aetrix Electronics and suitable for wireless sensor nodes, portable medical monitors, and industrial I/O modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LK112M28TR 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, sensors, and analog components 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 applications in battery-powered and signal-integrity-critical systems.

FAQ

What is the minimum input voltage required for regulation at 2.8 V output?

The LK112M28TR requires input voltage ≥ V_OUT + 0.5 V = 3.3 V for stable regulation. Below this threshold, dropout occurs and output voltage drops linearly with input. This specification holds across the full –40 °C to +125 °C junction temperature range and is verified per Table 5 in the official datasheet.

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 µV_rms output noise. Omitting this capacitor increases noise to >100 µV_rms, compromising signal integrity in precision analog circuits.

Does the LK112M28TR support reverse polarity protection?

No - the device lacks built-in reverse-voltage protection. Applying reversed input polarity may cause permanent damage. External protection (e.g., series Schottky diode or ideal diode controller) is required if reverse input is possible in the target application.

How does the shutdown current compare to similar LDOs in deep-sleep mode?

At 0.1 µA max in OFF mode, the LK112M28TR matches industry-leading ultra-low-I_q regulators like the TPS7A05. This value is measured at V_IN = 8 V and V_SHDN = 0 V, and remains stable across temperature - enabling multi-year battery life in duty-cycled IoT endpoints.

LK112M28TR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: SC-74A, SOT-753

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 14V

Voltage - Output (Min/Fixed):: 2.8V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.35V @ 150mA

Current - Output:: 150mA

Current - Quiescent (Iq):: 250 µA

Current - Supply (Max):: -

PSRR:: 55dB (400Hz)

Control Features:: Enable

Protection Features:: Over Current, Over Temperature

Operating Temperature:: -30°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

LK112M28TR FAQ

1.How can I place an order for LK112M28TR through Aetrix?

Please submit a Request for Quotation (RFQ) for LK112M28TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for LK112M28TR reliable?

The price and inventory of LK112M28TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LK112M28TR is usually 5 days.

3.What payment methods are accepted for LK112M28TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LK112M28TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LK112M28TR?

LK112M28TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LK112M28TR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for LK112M28TR?

For technical support, including LK112M28TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LK112M28TR requirements.

6.How does Aetrix verify that LK112M28TR is sourced from the original manufacturer or authorized distributors?

All LK112M28TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LK112M28TR meets industry standards.

7.What is the process for return or replacement of LK112M28TR?

All LK112M28TR units undergo pre-shipment inspection (PSI). If there is an issue with LK112M28TR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The LK112M28TR part is unused and in its original packaging.

Return procedure for LK112M28TR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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