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

Diodes Incorporated AP2121AK-3.3TRG1-1

Name: AP2121AK-3.3TRG1-1
Brand: Diodes Incorporated
SKU: AP2121AK-3.3TRG1-1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AP2121AK-3.3TRG1-1

Manufacturer:: Diodes Incorporated

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

Package:: SC-74A, SOT-753

Datasheet:: AP2121AK-3.3TRG1-1.pdf

Description:: IC REG LINEAR 3.3V 200MA SOT23-5

Quantity:: RFQ Add To RFQ list

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Product details

Overview

AP2121AK-3.3TRG1-1 from Diodes Incorporated is a high-speed, extremely low-noise 3.3V fixed-output LDO regulator in SOT-23-3 package, delivering up to 200mA output current with 150mV typical dropout at 100mA, 30µV_rms output noise (10Hz–100kHz), and ±2% output voltage accuracy. It serves as a precision local power rail for RF front-ends and analog signal chains in portable wireless devices.

For engineers reviewing the AP2121AK-3.3TRG1-1 datasheet, AP2121AK-3.3TRG1-1 pinout, AP2121AK-3.3TRG1-1 application, or AP2121AK-3.3TRG1-1 equivalent, key selection criteria include ultra-low noise performance, compatibility with 1µF ceramic output capacitors, high PSRR (70dB @ 1kHz), and operation across –40°C to +85°C ambient.

Technical Context

The AP2121AK-3.3TRG1-1 uses a CMOS-based error amplifier architecture with internal voltage reference and resistor network for fixed 3.3V output. Its low-quiescent-current design (25µA typical) enables battery longevity in always-on subsystems.

It features active-high enable control, thermal shutdown, and current-limit protection (50mA short-circuit limit). The device operates with input voltages from 2V to 6V and maintains regulation down to 3.3V + V_DROP, where V_DROP remains ≤150mV at 100mA load.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	3.3V ±2% - ensures stable biasing for 3.3V logic and analog ICs without external feedback.
Max Output Current	200mA continuous - sufficient for powering single-core microcontrollers or RF transceivers.
Dropout Voltage	150mV typ. @ 100mA - enables operation from 3.45V input, critical for Li-ion (3.0–4.2V) and dual-cell alkaline systems.
Output Noise	30µV_rms (10Hz–100kHz) - minimizes phase noise in VCOs and jitter in ADC clock domains.
PSRR	70dB @ 1kHz - suppresses switching noise from upstream DC/DC converters feeding the LDO input.
Quiescent Current	25µA typ. - extends battery life in sleep-mode applications such as IoT sensor nodes.
Enable Threshold	V_CE(HI) ≥1.5V - compatible with 1.8V/3.3V GPIOs without level-shifting.

Pinout & Package

SOT-23-3 package: 3-pin surface-mount, JEDEC standard footprint, 1.3mm × 2.9mm × 1.0mm body height, rated for 250°C/W junction-to-ambient thermal resistance.

Pin/Terminal	Circuit Role	Design Meaning
1 (VIN)	Input voltage supply	Accepts 2V–6V unregulated input; requires ≥1µF ceramic bypass capacitor.
2 (GND)	Ground reference	Common return path for input/output currents; must be low-impedance connection to system ground plane.
3 (VOUT)	Regulated output	Delivers stable 3.3V; supports ≥1µF ceramic output capacitor with ESR 0.01Ω–100Ω.

Key Features

Feature	Design Value
Ultra-low noise regulation	30µV_rms output noise enables clean power for RF receivers and precision ADCs.
Low dropout with high current	150mV dropout at 100mA allows efficient use of declining battery voltage in portable designs.
CMOS process architecture	Enables 25µA quiescent current and fast load transient response (<10µs settling).
1µF ceramic capacitor stability	Eliminates need for tantalum or electrolytic output capacitors, reducing board area and cost.
High PSRR at audio frequencies	70dB rejection at 1kHz prevents audible noise coupling into audio codecs or DACs.

Applications

Mobile RF Subsystem

Portable Audio Codec

Use Scenario: Powering 3.3V RF transceiver ICs (e.g., Bluetooth/BLE SoCs) in smartphones and wearables.

IC Role / Device Role / Timing Role: Local LDO providing ultra-low-noise VCC for RF synthesizer and receiver chain.

Use Value: 30µV_rms noise prevents reciprocal mixing and preserves receiver sensitivity below –100dBm.

Use Scenario: Supplying analog section of stereo audio codec in portable media players.

IC Role / Device Role / Timing Role: Clean 3.3V rail for DAC reference and analog output stage.

Use Value: 70dB PSRR blocks DC/DC ripple from corrupting THD+N performance below 0.01%.

IoT Sensor Node

Industrial Handheld Terminal

Use Scenario: Powering low-power MCU and analog sensor interface in battery-operated environmental sensors.

IC Role / Device Role / Timing Role: Primary regulated rail enabling deep-sleep mode with 25µA I_Q.

Use Value: 0.1µA standby current (with CE = low) extends 10-year battery life in sealed deployments.

Use Scenario: Providing stable 3.3V supply to touch controller and display driver in rugged handheld terminals.

IC Role / Device Role / Timing Role: Post-regulator after buck converter, rejecting switching noise in noisy industrial environments.

Use Value: ±2% output accuracy ensures reliable touch response and LCD contrast across temperature (–40°C to +85°C).

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
AP7343-33SG-7	Successor part; same 3.3V output, 300mA rating, 250mV dropout, 20µV_rms noise, and SOT-23-3 package.	Qualified per AEC-Q100 Grade 1; supports automotive infotainment and ADAS modules.	Select when new designs require extended lifecycle support, higher reliability, or automotive qualification.
MCP1700-3302E/TO	Microchip 3.3V LDO; 250mV dropout @ 250mA, 35µV_rms noise, 1.6µA quiescent current, TO-92 package.	Through-hole mounting; lower I_Q but larger footprint and no enable pin.	Choose only for legacy through-hole assembly or ultra-low-power (<2µA) sleep applications where enable control is unnecessary.

Compared with AP2121AK-3.3TRG1-1, AP7343-33SG-7 offers lower noise and automotive qualification but requires layout review for thermal derating above 150mA; MCP1700-3302E/TO trades enable functionality and SMT compatibility for sub-µA quiescent current in non-portable systems.

Availability

AP2121AK-3.3TRG1-1 is available at Aetrix Electronics and suitable for mobile RF subsystems, portable audio codecs, IoT sensor nodes, and industrial handheld terminals requiring stable component supply and long-term sourcing continuity.

Supply support for AP2121AK-3.3TRG1-1 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 semiconductor company specializing in discrete, analog, and mixed-signal solutions for power management, signal integrity, and connectivity applications.

The AP2121 series belongs to Diodes' high-performance LDO portfolio, designed specifically for noise-sensitive battery-powered electronics where low dropout, ultra-low noise, and minimal quiescent current are essential.

FAQ

What is the minimum input voltage required for AP2121AK-3.3TRG1-1 to maintain regulation?

The AP2121AK-3.3TRG1-1 requires VIN ≥ 3.45V to sustain 3.3V output at 100mA load, based on its 150mV typical dropout voltage. At lighter loads (e.g., 10mA), dropout drops to 20mV, allowing regulation down to 3.32V input. Operation below the dropout threshold results in pass transistor saturation and unregulated output.

Can AP2121AK-3.3TRG1-1 be used with a 1µF ceramic output capacitor?

Yes - the AP2121AK-3.3TRG1-1 is explicitly characterized for stability with 1µF ceramic capacitors having ESR between 0.01Ω and 100Ω. This eliminates the need for larger, less reliable tantalum or aluminum electrolytic capacitors and reduces PCB area by >50% compared to legacy LDOs requiring ≥10µF.

Does AP2121AK-3.3TRG1-1 include thermal shutdown protection?

Yes - the device integrates thermal shutdown circuitry that disables the output when junction temperature exceeds +150°C. Recovery occurs automatically once die temperature falls below the hysteresis threshold (~140°C). This protects against sustained overload or poor PCB thermal design without requiring external circuitry.

Is AP2121AK-3.3TRG1-1 recommended for new designs?

No - Diodes Incorporated states "THE AP2121 IS NOT RECOMMENDED FOR NEW DESIGNS. PLEASE USE THE AP7343." AP2121AK-3.3TRG1-1 remains available for existing production and legacy support, but AP7343-33SG-7 is the designated drop-in successor with improved noise, automotive qualification, and extended lifecycle commitment.

AP2121AK-3.3TRG1-1 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):: 0.5V @ 200mA

Current - Output:: 200mA

Current - Quiescent (Iq):: 50 µA

Current - Supply (Max):: -

PSRR:: 70dB (1kHz)

Control Features:: Enable

Protection Features:: Over Current

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

AP2121AK-3.3TRG1-1 FAQ

1.How can I place an order for AP2121AK-3.3TRG1-1 through Aetrix?

Please submit a Request for Quotation (RFQ) for AP2121AK-3.3TRG1-1 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 AP2121AK-3.3TRG1-1 reliable?

The price and inventory of AP2121AK-3.3TRG1-1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AP2121AK-3.3TRG1-1 is usually 5 days.

3.What payment methods are accepted for AP2121AK-3.3TRG1-1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AP2121AK-3.3TRG1-1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AP2121AK-3.3TRG1-1?

AP2121AK-3.3TRG1-1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AP2121AK-3.3TRG1-1 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 AP2121AK-3.3TRG1-1?

For technical support, including AP2121AK-3.3TRG1-1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AP2121AK-3.3TRG1-1 requirements.

6.How does Aetrix verify that AP2121AK-3.3TRG1-1 is sourced from the original manufacturer or authorized distributors?

All AP2121AK-3.3TRG1-1 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 AP2121AK-3.3TRG1-1 meets industry standards.

7.What is the process for return or replacement of AP2121AK-3.3TRG1-1?

All AP2121AK-3.3TRG1-1 units undergo pre-shipment inspection (PSI). If there is an issue with AP2121AK-3.3TRG1-1, 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 AP2121AK-3.3TRG1-1 part is unused and in its original packaging.

Return procedure for AP2121AK-3.3TRG1-1:

1.Submit a request within 90 days.

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

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