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

Diodes Incorporated AP2128K-3.3TRG1

Name: AP2128K-3.3TRG1
Brand: Diodes Incorporated
SKU: AP2128K-3.3TRG1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AP2128K-3.3TRG1

Manufacturer:: Diodes Incorporated

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

Package:: SC-74A, SOT-753

Datasheet:: AP2128K-3.3TRG1.pdf

Description:: IC REG LINEAR 3.3V 300MA SOT23-5

Quantity:: RFQ Add To RFQ list

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Inventory:32,855

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Product details

Overview

AP2128K-3.3TRG1 from BCD Semiconductor is a fixed-output 3.3V, 300mA CMOS low-dropout regulator in SOT-23-5 package, featuring 170mV dropout at full load, ±2% output voltage accuracy, and 60µV_rms output noise. It delivers stable power to noise-sensitive analog circuitry in portable computing and datacom systems with integrated thermal shutdown, short-circuit protection, and soft-start.

For engineers reviewing the AP2128K-3.3TRG1 datasheet, AP2128K-3.3TRG1 pinout, AP2128K-3.3TRG1 application, or AP2128K-3.3TRG1 equivalent, key selection criteria include dropout performance at 300mA, PSRR >68dB at 1kHz, standby current <1µA, and compatibility with 1µF ceramic input/output capacitors.

Technical Context

The AP2128K-3.3TRG1 uses a CMOS pass transistor architecture enabling ultra-low quiescent current (60µA typical) and extremely low output noise (60µV_rms). Its internal reference voltage is 0.8V, and output is regulated via feedback from VOUT directly-no external resistors required for fixed versions.

It integrates active shutdown control with logic-level compatible enable input (V_SHDN "High" ≥1.5V), auto-discharge MOSFET (R_DS(ON) = 60Ω), and thermal foldback that activates at 165°C with 30°C hysteresis. The device operates across -40°C to +85°C ambient with input range 2.5V–6V.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.3V ±2% - ensures stable supply for 3.3V logic, ADC references, and RF biasing without external resistor network.
Max Output Current	300mA continuous - supports moderate-power microcontrollers, sensors, and interface ICs in space-constrained designs.
Dropout Voltage	170mV @ 300mA - enables operation from 3.47V input, critical for single-cell Li-ion or multi-cell alkaline battery systems.
PSRR	68dB @ 1kHz - suppresses switching noise from upstream DC/DC converters feeding the LDO input.
Output Noise	60µV_rms (10Hz–100kHz) - preserves signal integrity in precision analog front-ends and clock generation circuits.
Quiescent Current	60µA typical - extends battery life in always-on monitoring and low-duty-cycle IoT endpoints.
Shutdown Current	0.1µA - enables deep-sleep modes in portable devices without compromising wake-up latency.

Pinout & Package

SOT-23-5 package: 2.82mm × 2.65mm × 1.3mm body, gull-wing leads, RoHS-compliant green finish (G1 suffix).

Pin/Terminal	Circuit Role	Design Meaning
VIN	Input voltage supply	Accepts 2.5V–6V; requires 1µF ceramic capacitor for stability and transient response.
GND	Ground reference	Common return path for input, output, and internal circuitry; must be low-impedance.
VOUT	Regulated output	Delivers fixed 3.3V ±2%; requires 1µF ceramic capacitor for loop stability and noise filtering.
SHUTDOWN	Enable/disable control	Active-high logic input; pulls VOUT to ground via 60Ω discharge MOSFET when low.
NC	No connect	Pin 5 is internally unconnected in fixed-output variants (K-package); must be left floating or grounded per layout best practice.

Key Features

Feature	Design Value
Low-noise regulation	60µV_rms output noise enables use in PLLs, ADCs, and RF synthesizers without added filtering.
Fast soft-start	50µs ramp time prevents inrush current and output overshoot during power-up sequences.
Ceramic capacitor compatible	Stable with 1µF C_IN/C_OUT - eliminates need for larger, less reliable tantalum or electrolytic capacitors.
Thermal & short-circuit protection	Auto-recovery thermal shutdown (165°C) and 50mA short-limit prevent damage under fault conditions.
Wide input range	2.5V–6V operation supports diverse sources: Li-ion, Li-Po, USB, and multi-cell alkaline/NiMH batteries.

Applications

Portable Data Acquisition

Notebook System Power

Use Scenario: Battery-powered handheld multimeter with 16-bit SAR ADC and LCD display.

IC Role / Device Role / Timing Role: Primary 3.3V analog supply for ADC reference, sensor interface, and microcontroller I/O rail.

Use Value: 60µV_rms noise and ±2% accuracy maintain 16-bit measurement fidelity without post-calibration drift.

Use Scenario: Standby power rail for chipset southbridge and embedded controller in ultrabook design.

IC Role / Device Role / Timing Role: Always-on 3.3V LDO supplying real-time clock, keyboard controller, and lid-open detection circuitry.

Use Value: 0.1µA shutdown current minimizes battery drain during sleep states exceeding 30 days.

Optical Transceiver Module

Industrial Sensor Node

Use Scenario: SFP+ module requiring clean 3.3V for laser driver bias and digital diagnostics interface.

IC Role / Device Role / Timing Role: Low-noise auxiliary supply decoupling high-speed serial data paths from noisy DC/DC converters.

Use Value: 68dB PSRR at 1kHz rejects ripple from 1MHz buck converter, preventing bit-error-rate degradation.

Use Scenario: Wireless temperature/humidity node powered by two AA cells with BLE SoC and analog sensor front-end.

IC Role / Device Role / Timing Role: Main system regulator delivering 3.3V to MCU, radio, and precision analog sensor conditioning.

Use Value: 170mV dropout allows >30% longer runtime vs. legacy LDOs when battery voltage drops below 3.5V.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MCP1700-3302E/TO	250mA max output, 175mV dropout @ 250mA, 65µV_rms noise, SOT-23-3 package (no shutdown pin)	Lacks enable/shutdown control and auto-discharge; limited to simpler always-on rails	Choose when board space is constrained and shutdown functionality is unnecessary.
Torex XC6206P332MR-G	300mA max, 200mV dropout @ 300mA, 40µV_rms noise, no thermal shutdown, SOT-25 package	Lower noise but no overtemperature protection; requires external thermal management	Prefer where ultra-low noise dominates reliability requirements and ambient temperature is tightly controlled.

Compared with MCP1700-3302E/TO and XC6206P332MR-G, the AP2128K-3.3TRG1 uniquely combines 300mA capability, integrated shutdown with discharge, thermal protection, and industry-leading PSRR-making it optimal for compact, robust, and noise-critical portable systems.

Availability

AP2128K-3.3TRG1 is available at Aetrix Electronics and suitable for notebook computers, optical transceivers, portable data acquisition, and industrial sensor nodes requiring stable component supply with guaranteed long-term sourcing.

Supply support for AP2128K-3.3TRG1 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

BCD Semiconductor Manufacturing Limited is a Shanghai-based fabless analog IC designer specializing in high-performance power management, LED drivers, and mixed-signal solutions for consumer, industrial, and communications markets.

The AP2128 series targets battery-powered and noise-sensitive applications demanding ultra-low quiescent current, high PSRR, and minimal footprint-reflecting BCD's focus on efficient, reliable, and application-optimized linear regulators.

FAQ

What is the minimum input voltage required for stable 3.3V output at 300mA?

The AP2128K-3.3TRG1 requires VIN ≥ 3.47V (3.3V + 170mV dropout) for full 300mA output. Below this, output voltage droops proportionally; operation down to 2.5V is supported at reduced load or higher VOUT tolerance.

Can AP2128K-3.3TRG1 replace adjustable LDOs like AP2128K-ADJTRG1 in existing designs?

No-AP2128K-3.3TRG1 is a fixed-output variant with NC on pin 5; the ADJ version uses pins 4 (ADJ) and 5 (GND) for resistor feedback. Pinout and internal topology differ, requiring PCB redesign and bill-of-material changes.

Is an input capacitor mandatory, and what value is recommended?

Yes-a 1µF X5R/X7R ceramic capacitor is mandatory at VIN for stability and transient response. Lower ESR improves PSRR and load step recovery; values <0.47µF risk oscillation per datasheet Figure 40 layout guidelines.

Does the SHUTDOWN pin require a pull-up resistor in normal operation?

No-internal pull-down resistance is 3MΩ, and the pin is logic-compatible with open-drain or push-pull controllers. A pull-up is only needed if driving from a high-impedance source; direct connection to MCU GPIO suffices.

AP2128K-3.3TRG1 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:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 6V

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

Voltage - Output (Max):: -

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

Current - Output:: 300mA

Current - Quiescent (Iq):: 90 µA

Current - Supply (Max):: -

PSRR:: 68dB ~ 54dB (100Hz ~ 10kHz)

Control Features:: Enable

Protection Features:: Over Current, Over Temperature

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

AP2128K-3.3TRG1 FAQ

1.How can I place an order for AP2128K-3.3TRG1 through Aetrix?

Please submit a Request for Quotation (RFQ) for AP2128K-3.3TRG1 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 AP2128K-3.3TRG1 reliable?

The price and inventory of AP2128K-3.3TRG1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AP2128K-3.3TRG1 is usually 5 days.

3.What payment methods are accepted for AP2128K-3.3TRG1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AP2128K-3.3TRG1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AP2128K-3.3TRG1?

AP2128K-3.3TRG1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AP2128K-3.3TRG1 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 AP2128K-3.3TRG1?

For technical support, including AP2128K-3.3TRG1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AP2128K-3.3TRG1 requirements.

6.How does Aetrix verify that AP2128K-3.3TRG1 is sourced from the original manufacturer or authorized distributors?

All AP2128K-3.3TRG1 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 AP2128K-3.3TRG1 meets industry standards.

7.What is the process for return or replacement of AP2128K-3.3TRG1?

All AP2128K-3.3TRG1 units undergo pre-shipment inspection (PSI). If there is an issue with AP2128K-3.3TRG1, 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 AP2128K-3.3TRG1 part is unused and in its original packaging.

Return procedure for AP2128K-3.3TRG1:

1.Submit a request within 90 days.

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

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