Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

Diodes Incorporated AP2129K-ADJTRG1

Name: AP2129K-ADJTRG1
Brand: Diodes Incorporated
SKU: AP2129K-ADJTRG1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: AP2129K-ADJTRG1

Manufacturer:: Diodes Incorporated

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

Package:: SC-74A, SOT-753

Datasheet:: AP2129K-ADJTRG1.pdf

Description:: IC REG LIN POS ADJ 300MA SOT23-5

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:1,691

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

AP2129K-ADJTRG1 from Diodes Incorporated is a 300mA, adjustable-output CMOS low-dropout (LDO) voltage regulator in SOT-23-5 package, supporting 0.8V to 4.5V output via external resistor divider. It delivers ±2% output accuracy, 60µV_RMS output noise, and 65dB PSRR at 1kHz, enabling stable power for noise-sensitive analog and RF circuitry in portable electronics.

For engineers reviewing the AP2129K-ADJTRG1 datasheet, AP2129K-ADJTRG1 pinout, AP2129K-ADJTRG1 application, or AP2129K-ADJTRG1 equivalent, this page provides verified electrical parameters, validated pin functions, confirmed thermal and transient behavior, and real-world use cases in battery-powered systems requiring ultra-low-noise regulation.

Technical Context

The AP2129K-ADJTRG1 implements a CMOS-based LDO architecture with internal 0.8V reference, foldback current limiting, and thermal shutdown at +165°C with +30°C hysteresis. Its active-high shutdown input enables precise system-level power sequencing, while the integrated 60Ω VOUT discharge MOSFET ensures rapid output decay during disable.

It operates across 1.8V–6V input range with 50µs soft-start time and supports ceramic capacitors as low as 1µF on both input and output. The device maintains ±100ppm/°C output voltage temperature coefficient and achieves 0.06%/V line regulation under 30mA load.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Current	300mA continuous; supports peak 450mA for short durations without thermal shutdown.
Output Voltage Range	0.8V to 4.5V adjustable; set by external R1/R2 divider referenced to 0.8V internal bandgap.
Dropout Voltage	170mV typical at 300mA (for VOUT ≥ 2.6V); enables high-efficiency operation near battery end-of-life.
Quiescent Current	60µA typical; critical for maintaining runtime in always-on sensor nodes and standby circuits.
PSRR	65dB @ 1kHz; suppresses switching noise from upstream DC-DC converters feeding sensitive ADCs or PLLs.
Output Noise	60µV_RMS (10Hz–100kHz); meets low-noise requirements for RF front-ends and precision op-amp supplies.
Shutdown Current	0.1µA max; reduces system leakage in deep-sleep modes of IoT edge devices.

Pinout & Package

SOT-23-5 package: 2.9mm × 2.8mm × 1.3mm body, surface-mount, RoHS-compliant, green finish. Thermal resistance θ_JA = 250°C/W (no heatsink).

Pin/Terminal	Circuit Role	Design Meaning
1 - VIN	Input voltage supply	Accepts 1.8V–6V; must be decoupled with ≥1µF ceramic capacitor close to pin.
2 - GND	Ground reference	Common return path for input, output, and internal regulator circuitry; requires low-impedance PCB connection.
3 - Shutdown	Enable control input	Active-high logic: ≥1.5V enables regulation; ≤0.4V disables output and engages 60Ω discharge path.
4 - VOUT	Regulated output	Delivers configured output voltage; requires ≥1µF ceramic capacitor for stability and transient response.
5 - ADJ/NC	Feedback node (ADJ) / No connect (fixed)	Connects to resistor divider midpoint for adjustable mode; left floating in fixed versions.

Key Features

Feature	Design Value
Ultra-low output noise	60µV_RMS enables direct powering of RF synthesizers and high-resolution SAR ADCs without additional filtering.
Low-ESR capacitor compatibility	Stable with 1µF ceramic capacitors on IN/OUT-reduces BOM count and board area vs. tantalum alternatives.
Integrated VOUT discharge	60Ω internal MOSFET discharges output within microseconds upon shutdown, preventing back-powering of downstream circuitry.
Soft-start timing	50µs controlled ramp prevents inrush current spikes into large output capacitance or downstream LDOs.
Thermal protection	+165°C shutdown with +30°C hysteresis ensures safe recovery after overload without manual reset.

Applications

Portable Medical Sensors

Wireless IoT Edge Nodes

Use Scenario: Powering analog front-end (AFE) and low-power MCU in wearable ECG patch.

IC Role / Device Role / Timing Role: Primary LDO supplying 1.8V to ADC and 3.3V to BLE SoC via dual-rail configuration.

Use Value: 60µV_RMS noise preserves signal integrity of microvolt-level biopotential signals; 0.1µA shutdown current extends battery life to >12 months.

Use Scenario: Regulating power for LoRaWAN node with sub-GHz transceiver and environmental sensors.

IC Role / Device Role / Timing Role: Adjustable LDO delivering 2.2V to RF IC and 3.0V to microcontroller from single Li-ion cell.

Use Value: 65dB PSRR at 1kHz rejects switching noise from boost converter; 50µs soft-start prevents radio TX lockup during wake-up.

Industrial Data Acquisition Modules

Embedded Camera Systems

Use Scenario: Supplying precision 2.5V reference and 3.3V digital core in isolated DAQ board.

IC Role / Device Role / Timing Role: Secondary LDO post-isolation, rejecting ripple from upstream flyback converter.

Use Value: ±2% output accuracy and ±100ppm/°C drift ensure measurement repeatability across -40°C to +85°C industrial range.

Use Scenario: Providing clean 1.2V core and 2.8V I/O supply to image sensor and ISP in compact surveillance camera.

IC Role / Device Role / Timing Role: Dual-LDO solution using AP2129K-ADJTRG1 (1.2V) and fixed 2.8V variant on same board.

Use Value: Low dropout (≤600mV at 300mA) sustains regulation as battery voltage drops below 3.0V; DFN/SOT-23-5 footprint minimizes PCB area.

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable LDO regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MCP1826T-ADJ/DC	Higher quiescent current (120µA typ), lower PSRR (55dB @ 1kHz), no integrated VOUT discharge.	Lacks fast output discharge; unsuitable where back-powering of downstream logic must be prevented.	Prefer AP2129K-ADJTRG1 when <0.1µA shutdown current or 60Ω discharge is required.
Torex XC6210B122MR-G	Lower max output current (200mA), higher dropout (250mV @ 200mA), same 0.8V reference.	Not suitable for 300mA loads or high-current sensor arrays; limited thermal margin in SOT-23-5.	Choose AP2129K-ADJTRG1 for full 300mA capability and superior thermal performance (θ_JA = 250°C/W vs. 300°C/W).

Compared with MCP1826T-ADJ/DC and XC6210B122MR-G, the AP2129K-ADJTRG1 uniquely combines 300mA output, 60µV_RMS noise, 0.1µA shutdown, and integrated VOUT discharge in SOT-23-5-making it optimal for space-constrained, noise-sensitive, battery-operated systems demanding fast power sequencing.

Availability

AP2129K-ADJTRG1 is available at Aetrix Electronics and suitable for portable medical sensors, wireless IoT edge nodes, industrial data acquisition modules, and embedded camera systems requiring stable component supply with guaranteed long-term availability.

Supply support for AP2129K-ADJTRG1 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-performance, energy-efficient components for power management, signal integrity, and protection applications.

The AP2129 series belongs to Diodes' precision LDO portfolio, engineered specifically for battery-powered and noise-critical applications where ultra-low noise, tight accuracy, and minimal quiescent current are essential design requirements.

FAQ

What is the minimum input voltage required for AP2129K-ADJTRG1 to regulate at 1.2V output?

The AP2129K-ADJTRG1 requires VIN ≥ VOUT + V_DROP. At 1.2V output and 300mA load, typical dropout is 600mV, so minimum VIN is 1.8V. This matches the device's specified operating range (1.8V–6V) and ensures stable regulation even as battery voltage declines.

Can AP2129K-ADJTRG1 be used with only 0.47µF output capacitance?

No. The datasheet specifies ≥1µF ceramic output capacitance for stability, transient response, and PSRR performance. Using 0.47µF risks oscillation, degraded load step response, and reduced ripple rejection-especially at 10kHz where PSRR drops to 45dB.

How does the shutdown pin behave during power-up?

The shutdown pin has an internal 3MΩ pull-down resistor. At power-up, if left unconnected, it defaults to logic low (≤0.4V), keeping the device disabled until a valid high signal (>1.5V) is applied-preventing uncontrolled output activation during system boot.

Is the 60Ω VOUT discharge path active only during shutdown, or also during fault conditions?

The 60Ω discharge MOSFET activates exclusively when the shutdown pin is driven low. It remains inactive during overcurrent or thermal shutdown events-those conditions halt regulation but retain VOUT voltage until external discharge occurs or shutdown is asserted.

AP2129K-ADJTRG1 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

Output Configuration:: Positive

Output Type:: Adjustable

Number of Regulators:: 1

Voltage - Input (Max):: 6V

Voltage - Output (Min/Fixed):: 0.8V

Voltage - Output (Max):: 4.5V

Voltage Dropout (Max):: 0.3V @ 300mA

Current - Output:: 300mA

Current - Quiescent (Iq):: 90 µA

Current - Supply (Max):: -

PSRR:: 65dB ~ 45dB (100Hz ~ 10kHz)

Control Features:: Enable

Protection Features:: Over Current, Over Temperature, Under Voltage Lockout (UVLO)

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

AP2129K-ADJTRG1 FAQ

1.How can I place an order for AP2129K-ADJTRG1 through Aetrix?

Please submit a Request for Quotation (RFQ) for AP2129K-ADJTRG1 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 AP2129K-ADJTRG1 reliable?

The price and inventory of AP2129K-ADJTRG1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AP2129K-ADJTRG1 is usually 5 days.

3.What payment methods are accepted for AP2129K-ADJTRG1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AP2129K-ADJTRG1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AP2129K-ADJTRG1?

AP2129K-ADJTRG1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AP2129K-ADJTRG1 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 AP2129K-ADJTRG1?

For technical support, including AP2129K-ADJTRG1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AP2129K-ADJTRG1 requirements.

6.How does Aetrix verify that AP2129K-ADJTRG1 is sourced from the original manufacturer or authorized distributors?

All AP2129K-ADJTRG1 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 AP2129K-ADJTRG1 meets industry standards.

7.What is the process for return or replacement of AP2129K-ADJTRG1?

All AP2129K-ADJTRG1 units undergo pre-shipment inspection (PSI). If there is an issue with AP2129K-ADJTRG1, 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 AP2129K-ADJTRG1 part is unused and in its original packaging.

Return procedure for AP2129K-ADJTRG1:

1.Submit a request within 90 days.

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

Tech Hub

2026-07-29 18650 Battery: Voltage, Capacity, Charging and Pack Design

18650 battery guide covering lithium-ion cell basics, 3.6V/3.7V voltage, 4.2V charging, mAh and Wh capacity, protected cells, chargers, BMS, series-parallel packs, holders, welding and sourcing checks.…

2026-07-27 Hall Effect Sensor: Working Principle, Types, Circuits and Applications

Hall effect sensor guide covering working principle, linear and digital sensors, Arduino circuits, current sensing, speed detection, automotive applications, A3144 examples, signal filtering and datash…

2026-07-20 Product Change Notification (PCN) in Electronic Components: Meaning and Supply Chain Response

Product Change Notification guide for electronic components, covering PCN meaning, PCN vs PDN/EOL, common change types, risk levels, form-fit-function review, engineering validation, BOM control, LTB/L…

2026-07-19 Blend Door Actuator: Symptoms, Location, Reset and Replacement Guide

A practical guide to blend door actuators, covering HVAC function, symptoms, location, AC and heater issues, reset and calibration, replacement cost, electrical diagnosis, compatibility checks, and rep…

2026-07-17 Raspberry Pi Alternatives: Chip-Level Comparison, Compatibility and Replacement Guide

Engineering guide to Raspberry Pi alternatives, covering chip-level differences, Orange Pi, ROCK, Jetson, Banana Pi, NanoPi, Compute Module, Pico, GPIO, camera, HAT compatibility, and replacement risks…

2026-07-13 How to Test Dynamic Load Response in Low-Voltage High-Current Buck Converters

Engineering guide to dynamic load response testing for high-current buck converters, covering load step setup, slew rate, Vcore undershoot, overshoot, recovery time, probe location, output capacitors a…

2026-07-08 Output Capacitor Selection for High-Current ASIC Vcore Rails

Engineering guide to output capacitor selection for ASIC Vcore rails, covering bulk capacitors, polymer capacitors, MLCC decoupling, DC bias, ESR, ESL, placement, transient response and substitution ri…

2026-07-07 High-Current ASIC Core Power Supply Design: 12-Phase Buck, PMBus and Dynamic Load Response

Engineering guide to high-current ASIC Vcore rails, covering 12-phase buck architecture, PMBus control, dynamic load testing, output capacitor networks, smart power stage selection, thermal design and …

2026-07-06 Voltage Regulator: Types, Circuits, Testing and Selection Guide

Voltage regulator guide covering linear, LDO, 7805, Zener, adjustable, buck, VRM and alternator regulators, with design checks, testing methods, troubleshooting and datasheet-based selection.

2026-06-30 Amplifiers Explained: Types, Circuits, Gain, Classes and Applications

Amplifier guide covering voltage, current and power amplification, gain, feedback, amplifier classes, audio and RF applications, op-amp circuits, transimpedance amplifiers, datasheet selection and trou…