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

Diodes Incorporated AP139-18WL-7

Name: AP139-18WL-7
Brand: Diodes Incorporated
SKU: AP139-18WL-7
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AP139-18WL-7

Manufacturer:: Diodes Incorporated

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

Package:: SC-74A, SOT-753

Datasheet:: AP139-18WL-7.pdf

Description:: IC REG LINEAR 1.8V 300MA SOT25

Quantity:: RFQ Add To RFQ list

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Product details

Overview

AP139-18WL-7 from Diodes Incorporated is a 1.8V, 300mA low-noise CMOS LDO regulator in SOT25 package, featuring 45μA typical quiescent current, 0.45V max dropout at 300mA, ±2% output voltage accuracy, and integrated thermal shutdown/current limiting-designed for battery-powered portable electronics requiring stable low-power biasing.

For engineers reviewing the AP139-18WL-7 datasheet, AP139-18WL-7 pinout, AP139-18WL-7 application, or AP139-18WL-7 equivalent, key selection criteria include dropout voltage at full load, PSRR performance at 1kHz/10kHz with 10nF BYP capacitor, EN pin threshold (1.7V ON / 0.8V OFF), stability with ≥1.0μF low-ESR output capacitor, and thermal shutdown activation at +130°C.

Technical Context

The AP139-18WL-7 employs a pMOS pass transistor architecture with internal voltage reference and error amplifier feedback loop, enabling precise regulation under varying load and line conditions. Its enable-controlled power-down mode reduces quiescent current to <2.0μA, while the dedicated BYP pin accepts a 10nF capacitor to suppress high-frequency noise and improve PSRR above 1kHz.

Thermal shutdown activates at +130°C junction temperature with +20°C hysteresis, and current limiting engages at 300–450mA depending on VOUT, ensuring safe operation during overload or short-circuit events. The device remains stable with ceramic output capacitors ≥1.0μF and ESR as low as 10mΩ.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 1.8V ±2% at 1mA, enabling direct powering of 1.8V logic rails without external resistors.
Max Output Current	Guaranteed 300mA continuous, supporting microcontrollers, sensors, and RF modules in compact portable designs.
Dropout Voltage	≤0.45V at 300mA (VOUT = 1.8V), allowing operation down to VIN = 2.25V-critical for single-cell Li-ion or two-cell alkaline systems.
Quiescent Current	45μA typ / 60μA max, minimizing battery drain in always-on or sleep-mode applications.
PSRR @ 1kHz	75dB with 10nF BYP capacitor, suppressing switching noise from upstream DC/DC converters feeding the LDO input.
Thermal Shutdown	Activates at TJ = +130°C with +20°C hysteresis, preventing permanent damage during sustained overload or poor PCB thermal design.
Input Voltage Range	2.7V to 5.5V, compatible with USB-powered, coin-cell, and multi-cell battery inputs without external regulators.

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 unregulated input; requires ≥0.1μF ceramic decoupling close to pin.
GND	Ground Reference	Common return path for all internal circuits and output capacitor; must connect to low-impedance ground plane.
EN	Enable Control Input	Active-high logic input (1.7V threshold); pulls low to disable regulator and reduce IQ to <2μA.
BYP	Noise Reduction Node	Connects to 10nF capacitor to GND to enhance PSRR >1kHz and stabilize internal reference.
VOUT	Regulated Output	Delivers stable 1.8V ±2% to load; requires ≥1.0μF low-ESR ceramic capacitor directly at pin.

Key Features

Feature	Design Value
Low-Noise Regulation	75dB PSRR at 1kHz with 10nF BYP cap enables clean supply for ADCs, PLLs, and RF receivers.
Ultra-Low Quiescent Current	45μA typ ensures >1-year battery life in 10μA average-load IoT sensors powered by CR2032 cells.
Robust Protection Suite	Integrated thermal shutdown (+130°C) and current limit (300–450mA) eliminate need for external protection circuitry.
Wide Input Compatibility	2.7–5.5V input range supports direct connection to USB ports, Li-ion batteries, and legacy 3.3V/5V rails.
Small-Footprint Stability	Stable with 1.0μF ceramic output capacitor-reduces BOM count and PCB area vs. larger tantalum alternatives.

Applications

Wearable Health Monitor

USB-Powered Peripheral

Use Scenario: Continuous ECG signal acquisition using ultra-low-power MCU and analog front-end.

IC Role / Device Role / Timing Role: Primary 1.8V bias rail for precision ADC and digital core, powered from coin cell or rechargeable LiPo.

Use Value: 45μA IQ extends battery runtime; 0.45V dropout allows operation until battery drops to 2.25V; 75dB PSRR prevents switching noise corruption of microvolt-level biopotential signals.

Use Scenario: Compact USB-to-serial adapter housing CP2102N and level-shifting logic.

IC Role / Device Role / Timing Role: Local 1.8V supply for 3.3V-to-1.8V level translators and I/O buffers, derived from 5V USB bus.

Use Value: Stable 1.8V rail maintains logic integrity across USB voltage variation (4.75–5.25V); EN pin enables firmware-controlled power gating during suspend mode.

Smart Home Sensor Node

Industrial Handheld Scanner

Use Scenario: Battery-operated Zigbee/Z-Wave temperature/humidity node with wake-on-event operation.

IC Role / Device Role / Timing Role: Always-on 1.8V supply for RF SoC sleep-state retention and wake-up timer circuitry.

Use Value: <2μA shutdown current preserves battery during multi-week idle periods; ±2% accuracy ensures consistent RF transmit power calibration across temperature.

Use Scenario: Rugged barcode scanner with OLED display, laser driver, and ARM Cortex-M4 MCU.

IC Role / Device Role / Timing Role: Secondary regulated rail for display controller and touch interface ICs, isolated from noisy motor/driver supplies.

Use Value: Thermal shutdown prevents failure during extended scanning sessions in hot environments; SOT25 footprint minimizes board space in constrained ergonomic housing.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
AP7343-18SAG-7	Successor device: 40μA IQ, 0.35V dropout at 300mA, improved PSRR (80dB @1kHz), same SOT25 package.	Pin-compatible replacement with enhanced efficiency and noise rejection; qualified for new designs per Diodes' NRND notice.	Select for new designs requiring longer battery life or higher noise immunity; verify BYP capacitor value per updated layout guidelines.
MCP1700T-1802E/TT	Microchip part: 1.8V, 250mA, 1.8μA IQ, 600mV dropout at 250mA, SOT23-5 package.	Lower IQ but reduced current capability and higher dropout; different pinout (GND/EN swapped) requires PCB redesign.	Consider only if ultra-low standby current dominates over load capacity and thermal margin; validate EN logic compatibility and thermal derating.

Compared with AP139-18WL-7, AP7343-18SAG-7 delivers measurable gains in efficiency and noise suppression while maintaining drop-in compatibility, whereas MCP1700T-1802E/TT trades output current and thermal robustness for extreme ultra-low-power operation in lighter-load scenarios.

Availability

AP139-18WL-7 is available at Aetrix Electronics and suitable for wearable health monitors, smart home sensor nodes, USB-powered peripherals, and industrial handheld scanners requiring stable component supply amid evolving obsolescence timelines.

Supply support for AP139-18WL-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 semiconductor company specializing in discrete, analog, and mixed-signal solutions, with manufacturing certified to IATF 16949 and product qualification per AEC-Q100/101 standards.

The AP139 belongs to Diodes' precision LDO regulator product line, engineered specifically for battery-constrained portable electronics where low IQ, low noise, and small footprint are non-negotiable design requirements.

FAQ

What is the minimum input voltage required for AP139-18WL-7 to maintain regulation at 300mA load?

The minimum input voltage is calculated as VOUT + VDROPOUT = 1.8V + 0.45V = 2.25V. At 300mA load and TA = +25°C, the device sustains regulation down to VIN = 2.25V. Below this, output voltage collapses linearly with input; operation below 2.7V is permitted but dropout increases as load rises.

Can AP139-18WL-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 compromises high-frequency noise rejection critical for sensitive analog circuits. The datasheet explicitly mandates this capacitor for specified PSRR performance and internal reference stability; operation without it may cause output ripple or regulation drift under dynamic load.

Is AP139-18WL-7 pin-compatible with AP7343-18SAG-7?

Yes-both devices use identical SOT25 pinout (VIN–GND–EN–BYP–VOUT) and share the same footprint, pad layout, and EN/BYP capacitor requirements. AP7343-18SAG-7 is Diodes' designated drop-in successor, offering improved specs while maintaining mechanical and electrical compatibility for seamless migration in existing designs.

Does AP139-18WL-7 require an input capacitor, and what value is recommended?

Yes-an input capacitor is required for stability and transient response. Diodes recommends ≥0.1μF ceramic capacitor placed as close as possible to the VIN and GND pins. For systems with long input traces or high-impedance sources (e.g., battery leads), a 1μF–10μF bulk capacitor is advised to suppress low-frequency ripple and prevent oscillation during load steps.

AP139-18WL-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):: 1.8V

Voltage - Output (Max):: -

Voltage Dropout (Max):: -

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

AP139-18WL-7 FAQ

1.How can I place an order for AP139-18WL-7 through Aetrix?

Please submit a Request for Quotation (RFQ) for AP139-18WL-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 AP139-18WL-7 reliable?

The price and inventory of AP139-18WL-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AP139-18WL-7 is usually 5 days.

3.What payment methods are accepted for AP139-18WL-7?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AP139-18WL-7 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AP139-18WL-7?

AP139-18WL-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AP139-18WL-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 AP139-18WL-7?

For technical support, including AP139-18WL-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AP139-18WL-7 requirements.

6.How does Aetrix verify that AP139-18WL-7 is sourced from the original manufacturer or authorized distributors?

All AP139-18WL-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 AP139-18WL-7 meets industry standards.

7.What is the process for return or replacement of AP139-18WL-7?

All AP139-18WL-7 units undergo pre-shipment inspection (PSI). If there is an issue with AP139-18WL-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 AP139-18WL-7 part is unused and in its original packaging.

Return procedure for AP139-18WL-7:

1.Submit a request within 90 days.

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

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