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

STMicroelectronics LK112M33TR

Name: LK112M33TR
Brand: STMicroelectronics
SKU: LK112M33TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LK112M33TR

Manufacturer:: STMicroelectronics

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

Package:: SC-74A, SOT-753

Datasheet:: LK112M33TR.pdf

Description:: IC REG LINEAR 3.3V 150MA SOT23-5

Quantity:: RFQ Add To RFQ list

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Inventory:15,494

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Product details

Overview

LK112M33TR from STMicroelectronics is a 3.3 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. Used in portable instrumentation and sensor signal chains where stable, clean power is critical.

For engineers reviewing the LK112M33TR datasheet, LK112M33TR pinout, LK112M33TR application, or LK112M33TR equivalent, key selection criteria include dropout voltage at 150 mA, output noise performance with 0.1 µF bypass capacitor, shutdown logic threshold (0.6 V), thermal shutdown at 150 °C, and SOT23-5L package compatibility with space-constrained PCB layouts.

Technical Context

The LK112M33TR employs an internal PNP pass transistor to achieve low dropout and high PSRR (55 dB at 400 Hz). Its TTL/CMOS-compatible SHDN pin enables precise system-level power sequencing, with shutdown current below 100 nA.

It integrates overcurrent and thermal protection-automatically disabling output during short-circuit or junction temperature >150 °C-and uses an external 0.1 µF capacitor on the Bypass pin to reduce output noise to 30 µV_rms across 10 Hz–80 kHz bandwidth.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	3.3 V ±2 % - tightly regulated rail for 3.3 V logic and analog ICs
Max Output Current	150 mA - sufficient for microcontrollers, ADCs, and RF front-ends
Dropout Voltage	350 mV at 150 mA - enables operation down to VIN = 3.65 V for 3.3 V output
Quiescent Current	250 µA max (ON), 0.1 µA (OFF) - extends battery life in sleep-mode applications
Output Noise	30 µV_rms (10 Hz–80 kHz) - supports low-noise op-amps and precision sensors
PSRR	55 dB at 400 Hz - suppresses ripple from noisy DC-DC converters
Shutdown Threshold	V_SHDN ≤ 0.6 V disables regulator - compatible with standard GPIO logic levels

Pinout & Package

Supplied in SOT23-5L package: compact, surface-mount, thermally enhanced (R_thJA = 255 °C/W), with die attach flag internally connected to GND for improved heat dissipation.

Pin/Terminal	Circuit Role	Design Meaning
1 - SHDN	Active-low enable input	Pulled low (<0.6 V) to disable regulator; TTL/CMOS compatible; draws ≤35 µA when active
2 - GND	Power ground	Internally bonded to die attach flag - lowers thermal resistance and improves power handling
3 - Bypass	Noise reduction node	Connects external 0.1 µF capacitor to reduce output noise to 30 µV_rms
4 - OUT	Regulated output	Delivers stable 3.3 V ±2 % up to 150 mA; requires ≥2.2 µF ceramic output capacitor
5 - IN	Input supply	Accepts 3.8 V to 14 V (for 3.3 V output); minimum headroom = V_OUT + 0.5 V

Key Features

Feature	Design Value
Ultra-low noise regulation	30 µV_rms output noise with 0.1 µF bypass cap - eliminates need for post-LDO filtering in sensitive analog stages
Sub-µA shutdown current	0.1 µA max I_Q in OFF mode - preserves battery charge during extended idle periods
Integrated protection	Thermal shutdown (150 °C) and current limiting (150 mA) - prevents damage under fault conditions without external circuitry
Logic-compatible enable	SHDN pin accepts 0–1.8 V for OFF and ≥1.8 V for ON - simplifies interface with MCU GPIOs
Low dropout architecture	350 mV dropout at 150 mA - maximizes usable battery voltage range in single-cell Li-ion or 2xAA systems

Applications

Portable Medical Sensors

Industrial Data Acquisition

Use Scenario: Powering low-power analog front-ends in handheld ECG or pulse oximeter modules.

IC Role / Device Role / Timing Role: Primary 3.3 V supply for precision ADCs and instrumentation amplifiers requiring <50 µV noise floor.

Use Value: 30 µV_rms noise and 0.1 µA shutdown current directly extend battery runtime while preserving signal integrity.

Use Scenario: Regulating power for isolated 24-bit sigma-delta ADCs in PLC analog input modules.

IC Role / Device Role / Timing Role: Clean, stable 3.3 V reference rail decoupled from noisy 5 V or 24 V system supplies via LDO stage.

Use Value: 55 dB PSRR at 400 Hz suppresses switching noise from upstream DC-DC converters, improving ENOB by ≥0.5 bits.

Wireless IoT Endpoints

Automotive Body Control Modules

Use Scenario: Supplying BLE SoCs and environmental sensors in battery-operated smart meters.

IC Role / Device Role / Timing Role: Always-on LDO with programmable shutdown for deep-sleep wake-up cycles.

Use Value: 0.1 µA OFF-mode current reduces annual self-discharge to <1 % of typical CR2032 capacity.

Use Scenario: Powering CAN transceiver bias rails and microcontroller I/O banks in non-safety-critical body electronics.

IC Role / Device Role / Timing Role: Secondary 3.3 V regulator fed from main 5 V domain, with thermal protection for under-hood ambient.

Use Value: Junction temperature limit of 150 °C ensures reliable operation up to +125 °C ambient in engine bay proximity.

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
TCS2117-3.3V	Higher dropout (500 mV @ 150 mA); 45 µV_rms noise; no dedicated bypass pin	Lacks Bypass pin optimization - requires larger output capacitance for same noise performance	Select if board layout prohibits 0.1 µF bypass capacitor placement near LDO
MCP1703T-3302E/MB	Lower quiescent current (2 µA ON, 100 nA OFF); 40 µV_rms noise; SOT-23-3 package (no SHDN)	No enable pin - unsuitable for dynamic power gating; fixed 3-pin configuration limits flexibility	Select only for always-on, ultra-low-I_Q applications where shutdown control is unnecessary

Compared with TCS2117-3.3V and MCP1703T-3302E/MB, the LK112M33TR uniquely balances ultra-low noise (30 µV_rms), sub-µA shutdown, and logic-controlled enable in a 5-pin thermally optimized package-making it optimal for battery-powered systems requiring both precision and power-state agility.

Availability

LK112M33TR is available at Aetrix Electronics and suitable for portable medical sensors, industrial data acquisition modules, and wireless IoT endpoints requiring stable component supply with guaranteed long-term manufacturability.

Supply support for LK112M33TR 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 noise-sensitive, battery-constrained applications demanding high PSRR, low I_Q, and robust fault protection in minimal footprint.

FAQ

What is the minimum input voltage required for stable 3.3 V output?

The LK112M33TR requires a minimum input voltage of V_OUT + 0.5 V = 3.8 V under normal operation. For inputs below 3.8 V, regulation degrades and dropout increases nonlinearly. The absolute minimum specified input is 2.5 V, but this applies only to versions with V_OUT < 2 V - not applicable here.

Can the Bypass pin be left unconnected?

No. Leaving the Bypass pin floating degrades noise performance: output noise rises from 30 µV_rms to >100 µV_rms. ST specifies a 0.1 µF ceramic capacitor between Bypass and GND to achieve rated noise performance. Omitting it compromises the primary low-noise advantage of this device.

Does the LK112M33TR support reverse polarity or reverse current protection?

No. The device lacks built-in reverse-voltage or reverse-current protection. If input polarity reversal is possible in the system, an external series Schottky diode or ideal diode controller must be added. Reverse current flow from OUT to IN is not blocked and may occur if V_IN < V_OUT.

Is the SOT23-5L package RoHS and REACH compliant?

Yes. Per STMicroelectronics ECOPACK® documentation, the SOT23-5L package used for LK112M33TR meets RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006, including lead-free terminations and halogen-free molding compound. Full compliance data is available in ST's ECOPACK® database at www.st.com.

LK112M33TR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 14V

Voltage - Output (Min/Fixed):: 3.3V

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

LK112M33TR FAQ

1.How can I place an order for LK112M33TR through Aetrix?

Please submit a Request for Quotation (RFQ) for LK112M33TR 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 LK112M33TR reliable?

The price and inventory of LK112M33TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LK112M33TR is usually 5 days.

3.What payment methods are accepted for LK112M33TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LK112M33TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LK112M33TR?

LK112M33TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LK112M33TR 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 LK112M33TR?

For technical support, including LK112M33TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LK112M33TR requirements.

6.How does Aetrix verify that LK112M33TR is sourced from the original manufacturer or authorized distributors?

All LK112M33TR 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 LK112M33TR meets industry standards.

7.What is the process for return or replacement of LK112M33TR?

All LK112M33TR units undergo pre-shipment inspection (PSI). If there is an issue with LK112M33TR, 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 LK112M33TR part is unused and in its original packaging.

Return procedure for LK112M33TR:

1.Submit a request within 90 days.

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

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