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

STMicroelectronics LK112M36TR

Name: LK112M36TR
Brand: STMicroelectronics
SKU: LK112M36TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LK112M36TR

Manufacturer:: STMicroelectronics

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

Package:: SC-74A, SOT-753

Datasheet:: LK112M36TR.pdf

Description:: IC REG LINEAR 3.6V 150MA SOT23-5

Quantity:: RFQ Add To RFQ list

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Inventory:2,674

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Product details

Overview

LK112M36TR from STMicroelectronics is a low-noise, low-dropout linear voltage regulator with integrated shutdown control and 3.6 V fixed output. It delivers up to 150 mA, maintains 350 mV dropout at full load, achieves 30 µV_RMS output noise (10 Hz–80 kHz), and draws only 250 µA quiescent current in ON mode. It powers precision analog sensors and low-power microcontrollers in battery-operated IoT edge nodes.

For engineers reviewing the LK112M36TR datasheet, LK112M36TR pinout, LK112M36TR application, or LK112M36TR equivalent, key selection criteria include its 3.6 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 LK112M36TR uses an internal PNP pass transistor to achieve low dropout and stable regulation across input voltages from 4.1 V (V_OUT + 0.5 V) to 14 V. Its shutdown logic accepts TTL/CMOS-level signals on the SHDN pin, reducing quiescent current to ≤0.1 µA when asserted low.

Noise performance is enhanced via a dedicated Bypass pin accepting a 0.1 µF capacitor, lowering output noise to 30 µV_RMS. Internal protection includes thermal shutdown (T_J < 150 °C), short-circuit current limiting, and overcurrent foldback-no external components required.

Key Specifications

Parameter	Value and Actual Design Meaning
Output voltage	Fixed 3.6 V ±2 % - ensures stable supply for 3.3 V–3.6 V logic and analog circuitry without external feedback.
Max output current	150 mA - supports moderate-current loads like RF transceivers or multi-sensor modules.
Dropout voltage	350 mV at 150 mA - enables operation from single Li-ion (3.0–4.2 V) or two alkaline cells (3.0–3.2 V).
Quiescent current	250 µA max in ON mode, 0.1 µA in OFF mode - extends battery life in sleep-wake cycling applications.
Output noise	30 µV_RMS (10 Hz–80 kHz) with 0.1 µF bypass - meets noise-sensitive requirements of ADC references and op-amp signal chains.
Supply rejection	55 dB at 400 Hz - suppresses ripple from noisy switching supplies feeding the LDO input.
Operating junction temp	−40 °C to +125 °C - qualified for industrial and extended-temperature embedded environments.

Pinout & Package

SOT23-5L package: compact 5-pin surface-mount outline with exposed die attach flag for improved thermal dissipation (R_thJA = 255 °C/W, R_thJC = 81 °C/W).

Pin/Terminal	Circuit Role	Design Meaning
1 - SHDN	Shutdown control input	TTL/CMOS-compatible enable pin; logic high (>1.8 V) activates regulator, logic low (<0.6 V) disables output and reduces I_q to ≤0.1 µA.
2 - GND	Ground reference	Internally connected to die attach flag to minimize thermal resistance and improve 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	3.6 V fixed output capable of sourcing up to 150 mA with ±2 % accuracy and <90 mV load regulation (1–150 mA).
5 - IN	Input supply	Accepts 4.1 V to 14 V DC; requires ≥1 µF ceramic input capacitor for stability and transient response.

Key Features

Feature	Design Value
Low-noise regulation	30 µV_RMS output noise (10 Hz–80 kHz) with 0.1 µF bypass cap - enables clean power for precision ADCs and RF ICs.
Ultra-low shutdown current	≤0.1 µA I_q in OFF mode - preserves battery charge during extended system sleep states.
Integrated protection	Thermal shutdown (150 °C), current limit (150 mA), and short-circuit foldback - eliminates need for external fault-handling circuitry.
Wide input range	Operates from V_OUT + 0.5 V (4.1 V) to 14 V - compatible with diverse input sources including buck converters and multi-cell batteries.
Stable with small capacitors	Guaranteed stability with 2.2 µF ceramic output capacitor - reduces BOM count and board area vs. larger tantalum alternatives.

Applications

Wireless Sensor Node Power

Portable Medical Monitor

Use Scenario: Battery-powered temperature/humidity sensor transmitting data via BLE every 5 seconds.

IC Role / Device Role / Timing Role: Primary 3.6 V supply for MCU, BLE radio, and analog front-end.

Use Value: 30 µV_RMS noise ensures accurate 12-bit ADC readings; 0.1 µA shutdown current extends 2-year battery life.

Use Scenario: Handheld pulse oximeter using optical sensing and low-power display.

IC Role / Device Role / Timing Role: Clean 3.6 V rail for photodiode amplifier and ADC reference.

Use Value: Low dropout allows operation down to 3.7 V battery voltage; thermal protection prevents overheating during extended use.

Industrial PLC I/O Module

Smart Meter Analog Front-End

Use Scenario: DIN-rail mounted sensor interface module operating in −25 °C to +70 °C ambient.

IC Role / Device Role / Timing Role: Local 3.6 V regulator for isolated analog signal conditioning and SPI interface ICs.

Use Value: −40 °C to +125 °C junction rating ensures reliability; 55 dB PSRR rejects switching noise from adjacent DC/DC converters.

Use Scenario: Electricity meter with metrology-grade ADC and real-time clock.

IC Role / Device Role / Timing Role: Dedicated low-noise supply for ADC reference and precision op-amps.

Use Value: 30 µV_RMS noise directly improves ENOB; internal current limit protects against metering circuit faults.

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
AP2210K-3.6TRG1	Higher dropout (500 mV @ 150 mA), higher noise (45 µV_RMS), no dedicated bypass pin	Lacks noise optimization path; less suitable for metrology-grade analog rails	Choose if cost sensitivity outweighs noise/dropout requirements and bypass cap integration is unnecessary.
MCP1703T-3602E/MB	Lower quiescent current in ON mode (4 µA), but only 250 mA max output and no thermal shutdown	Missing overtemperature protection; unsuitable for enclosed or high-ambient environments	Prefer where ultra-low I_q dominates and thermal margin is guaranteed by system design.

Compared with AP2210K-3.6TRG1 and MCP1703T-3602E/MB, the LK112M36TR uniquely combines 30 µV_RMS noise, 350 mV dropout, and full thermal/current protection in SOT23-5L-making it optimal for space-constrained, battery-powered precision analog systems requiring robust fault tolerance.

Availability

LK112M36TR is available at Aetrix Electronics and suitable for wireless sensor nodes, portable medical monitors, industrial I/O modules, and smart meter analog front-ends requiring stable component supply with consistent parametric performance and long-term manufacturability.

Supply support for LK112M36TR 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-dropout regulator product line, engineered specifically for battery-powered and noise-sensitive applications where ultra-low quiescent current, low noise, and integrated protection are critical.

FAQ

What is the minimum input voltage required for the LK112M36TR to regulate at 3.6 V?

The LK112M36TR requires a minimum input voltage of V_OUT + 0.5 V = 4.1 V for proper regulation. This is specified in the datasheet under "Operative input voltage" for V_OUT > 2 V. Below this threshold, dropout behavior occurs and output voltage drops linearly with input.

Can the Bypass pin be left unconnected?

No. Leaving the Bypass pin floating degrades noise performance: output noise rises from 30 µV_RMS to ~120 µV_RMS. The datasheet mandates a 0.1 µF ceramic capacitor between Bypass and GND to achieve specified low-noise operation and ensure stability.

Does the LK112M36TR require an input capacitor?

Yes. A minimum 1 µF ceramic input capacitor is required for stability and transient response, as confirmed in Section 4 ("Electrical characteristics") test conditions and Figure 21 ("Stability"). Omitting it risks oscillation and poor line regulation, especially with long PCB traces.

How does the shutdown function interact with thermal protection?

Shutdown and thermal protection operate independently: asserting SHDN low disables regulation and cuts I_q to ≤0.1 µA, but thermal shutdown remains active and will force output disable if junction temperature exceeds 150 °C-even during shutdown. Both mechanisms protect the die, but thermal shutdown overrides shutdown state during fault conditions.

LK112M36TR 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):: 3.6V

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

LK112M36TR FAQ

1.How can I place an order for LK112M36TR through Aetrix?

Please submit a Request for Quotation (RFQ) for LK112M36TR 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 LK112M36TR reliable?

The price and inventory of LK112M36TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LK112M36TR is usually 5 days.

3.What payment methods are accepted for LK112M36TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LK112M36TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LK112M36TR?

LK112M36TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LK112M36TR 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 LK112M36TR?

For technical support, including LK112M36TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LK112M36TR requirements.

6.How does Aetrix verify that LK112M36TR is sourced from the original manufacturer or authorized distributors?

All LK112M36TR 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 LK112M36TR meets industry standards.

7.What is the process for return or replacement of LK112M36TR?

All LK112M36TR units undergo pre-shipment inspection (PSI). If there is an issue with LK112M36TR, 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 LK112M36TR part is unused and in its original packaging.

Return procedure for LK112M36TR:

1.Submit a request within 90 days.

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

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