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

Diodes Incorporated AP139-35WG-7

Name: AP139-35WG-7
Brand: Diodes Incorporated
SKU: AP139-35WG-7
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AP139-35WG-7

Manufacturer:: Diodes Incorporated

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

Package:: SC-74A, SOT-753

Datasheet:: AP139-35WG-7.pdf

Description:: IC REG LINEAR 3.5V 300MA SOT25

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Product details

Overview

AP139-35WG-7 from Diodes Incorporated is a 3.5V fixed-output, 300mA CMOS low-dropout linear regulator in SOT25 package, featuring 45μA typical quiescent current, 0.45V max dropout at 300mA, ±2% output voltage accuracy, and integrated thermal shutdown and current limiting-designed for battery-powered portable electronics requiring stable low-noise supply.

For engineers reviewing the AP139-35WG-7 datasheet, AP139-35WG-7 pinout, AP139-35WG-7 application, or AP139-35WG-7 equivalent, key selection criteria include dropout voltage at full load, PSRR performance (75dB @1kHz with 10nF bypass), enable pin threshold (1.7V high), standby current (<2μA), and stability with ≥1.0μF low-ESR ceramic output capacitors.

Technical Context

The AP139 employs a pMOS pass transistor architecture enabling ultra-low dropout and near-zero gate-drive current, paired with a precision bandgap reference and error amplifier delivering ±2% output regulation across temperature and line/load variations. Its internal current-limit circuit activates at 300mA (min) and thermal shutdown engages at +130°C junction temperature with +20°C hysteresis.

Operation requires external 10nF bypass capacitor between BYP and GND to achieve optimal noise suppression and PSRR enhancement-particularly critical at 1–100kHz-while maintaining stability with ≥1.0μF output capacitance regardless of ESR value, eliminating need for specialized low-ESR tantalum or polymer types.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.5V ±2% - ensures precise rail generation for 3.3V-tolerant logic without external feedback network
Max Output Current	300mA guaranteed - supports moderate-power microcontrollers, sensors, and RF front-ends in compact devices
Dropout Voltage	≤0.45V at 300mA - enables operation down to VIN = 3.95V, extending battery runtime in single-cell Li-ion or 3×AA systems
Quiescent Current	45μA typ / 60μA max - minimizes standby drain in always-on wearable or IoT edge nodes
PSRR @1kHz	75dB with 10nF BYP cap - suppresses switching noise from adjacent DC/DC converters in mixed-signal PCBs
Enable Threshold	V_EH = 1.7V min - compatible with 1.8V/3.3V GPIO control without level-shifting
Thermal Shutdown	Triggers at T_J = +130°C - protects against sustained overload or poor PCB thermal design

Pinout & Package

SOT25 (5-pin, 2.9mm × 1.6mm × 1.1mm) surface-mount package with exposed thermal pad (not electrically connected); RoHS-compliant, halogen-free "Green" construction.

Pin/Terminal	Circuit Role	Design Meaning
VIN	Input Power Supply	Accepts 2.7–5.5V input; must be decoupled with ≥0.1μF capacitor close to pin
GND	Ground Reference	Primary return path for load, bias, and bypass currents; requires low-impedance PCB connection
EN	Enable Control Input	Active-high logic input; pulls <2μA when disabled; floats high by default
BYP	Bypass Capacitor Terminal	Connects to 10nF capacitor to ground to reduce internal reference noise and boost PSRR
VOUT	Regulated Output	Delivers stable 3.5V; requires ≥1.0μF low-ESR ceramic capacitor directly at pin

Key Features

Feature	Design Value
Low-noise regulation	10nF BYP capacitor reduces output voltage noise floor and enables 75dB PSRR @1kHz
Ultra-low IQ operation	45μA typical quiescent current extends shelf life and runtime in battery-gated systems
Robust protection suite	Integrated current limit (300–450mA) and thermal shutdown (+130°C) prevent field failures
Flexible capacitor compatibility	Stable with ≥1.0μF ceramic output caps-no ESR constraints simplify BOM and layout
Precision output accuracy	±2% over temperature and line/load ensures reliable interface with 3.3V I/O peripherals

Applications

Wireless Headsets

Smart Wearables

Use Scenario: Compact Bluetooth audio receiver powered by single-cell lithium-polymer battery (3.0–4.2V).

IC Role / Device Role / Timing Role: Primary 3.5V LDO supplying codec, Bluetooth SoC core, and analog front-end.

Use Value: 0.45V dropout preserves >30 minutes of playback at end-of-battery discharge; 45μA IQ extends standby time to >14 days.

Use Scenario: Fitness tracker with optical heart-rate sensor, accelerometer, and BLE radio operating intermittently.

IC Role / Device Role / Timing Role: Always-on 3.5V rail for real-time clock, sensor interface, and wake-up controller.

Use Value: <2μA shutdown current during deep sleep mode; ±2% accuracy maintains sensor ADC reference integrity across -10°C to +50°C.

USB-C Peripheral Hubs

Industrial Handheld Scanners

Use Scenario: Bus-powered USB-C dock providing 3.5V to embedded microcontroller and level translators.

IC Role / Device Role / Timing Role: Local regulation stage isolating MCU from noisy upstream 5V VBUS.

Use Value: 75dB PSRR at 1kHz rejects USB switching noise; EN pin enables dynamic power gating per port activity.

Use Scenario: Rugged barcode scanner using alkaline AA batteries (2.4–3.2V under load) with integrated display and imager.

IC Role / Device Role / Timing Role: Main 3.5V supply for image sensor, display driver, and decode processor.

Use Value: Thermal shutdown prevents damage during extended scanning bursts; SOT25 footprint fits tight mechanical envelope.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
AP7343-35SAG-7	Successor device: lower IQ (2.5μA typ), improved PSRR (80dB @1kHz), same SOT25 package and 3.5V output	Designed for next-gen ultra-low-power designs; pin-compatible drop-in replacement	Select for new designs requiring longer battery life and higher noise immunity
MCP1700-3302E/TO	3.3V fixed output, TO-92 package, 2.3μA IQ, but only 250mA rated output and no BYP pin	Limited to low-current, non-noise-sensitive applications; through-hole mounting only	Consider only if cost sensitivity outweighs performance and footprint requirements

Compared with AP139-35WG-7, AP7343-35SAG-7 delivers 18× lower quiescent current and 5dB higher PSRR while maintaining identical pinout and thermal behavior-making it the preferred choice for new designs. MCP1700-3302E/TO trades performance and integration for legacy through-hole compatibility and lower unit cost in low-volume applications.

Availability

AP139-35WG-7 is available at Aetrix Electronics and suitable for wireless headsets, smart wearables, USB-C peripheral hubs, and industrial handheld scanners requiring stable component supply with consistent parametric performance and long-term traceability.

Supply support for AP139-35WG-7 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-reliability power management, signal integrity, and protection solutions for consumer, industrial, and automotive markets.

The AP139 belongs to Diodes' CMOS LDO regulator product line, engineered specifically for space-constrained, battery-operated portable electronics where low dropout, ultra-low IQ, and robust protection are mandatory-not general-purpose power conversion.

FAQ

What is the minimum input voltage required for AP139-35WG-7 to maintain regulation at 300mA load?

The minimum input voltage is calculated as V_OUT + V_DROPOUT = 3.5V + 0.45V = 3.95V. Below this, output voltage drops linearly with input. This value is confirmed in the datasheet's Absolute Maximum Ratings and Electrical Characteristics tables under V_DROPOUT test conditions at I_OUT = 300mA and V_OUT ≥ 2.8V.

Can AP139-35WG-7 operate without the 10nF bypass capacitor on the BYP pin?

No-omitting the 10nF BYP capacitor degrades PSRR by up to 25dB at 1kHz and increases output noise significantly. The datasheet explicitly states this capacitor is "necessary" for low-noise operation and specifies its placement between BYP and GND. Stability remains unaffected, but noise performance falls outside specification.

Is AP139-35WG-7 qualified for automotive applications?

No-AP139-35WG-7 is not AEC-Q100 qualified. The datasheet notes that automotive-grade variants require specific change control, PPAP capability, and IATF 16949 manufacturing; this part is marked NRND (Not Recommended for New Designs) and intended for commercial portable electronics only.

How does the EN pin behave when left unconnected?

When unconnected, the EN pin floats high due to internal pull-up, enabling normal regulator operation. The datasheet confirms EN "normally floats high" and draws <0.1μA. No external pull-up is required, but for deterministic startup in noisy environments, a 100kΩ resistor to VIN is recommended.

AP139-35WG-7 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

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):: 5.5V

Voltage - Output (Min/Fixed):: 3.5V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.45V @ 300mA

Current - Output:: 300mA

Current - Quiescent (Iq):: 60 µA

Current - Supply (Max):: -

PSRR:: 75dB ~ 30dB (1KHz ~ 100KHz)

Control Features:: Enable

Protection Features:: Over Current, Over Temperature, Short Circuit

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-25

AP139-35WG-7 FAQ

1.How can I place an order for AP139-35WG-7 through Aetrix?

Please submit a Request for Quotation (RFQ) for AP139-35WG-7 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 AP139-35WG-7 reliable?

The price and inventory of AP139-35WG-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AP139-35WG-7 is usually 5 days.

3.What payment methods are accepted for AP139-35WG-7?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AP139-35WG-7 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AP139-35WG-7?

AP139-35WG-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AP139-35WG-7 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 AP139-35WG-7?

For technical support, including AP139-35WG-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AP139-35WG-7 requirements.

6.How does Aetrix verify that AP139-35WG-7 is sourced from the original manufacturer or authorized distributors?

All AP139-35WG-7 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 AP139-35WG-7 meets industry standards.

7.What is the process for return or replacement of AP139-35WG-7?

All AP139-35WG-7 units undergo pre-shipment inspection (PSI). If there is an issue with AP139-35WG-7, 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 AP139-35WG-7 part is unused and in its original packaging.

Return procedure for AP139-35WG-7:

1.Submit a request within 90 days.

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

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