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

Diodes Incorporated AP7351D-45FS4-7B

Name: AP7351D-45FS4-7B
Brand: Diodes Incorporated
SKU: AP7351D-45FS4-7B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AP7351D-45FS4-7B

Manufacturer:: Diodes Incorporated

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

Package:: 4-XDFN Exposed Pad

Datasheet:: AP7351D-45FS4-7B.pdf

Description:: LDO CMOS LOWCURR X2-DFN1010-4 (T

Quantity:: RFQ Add To RFQ list

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Product details

Overview

AP7351D-45FS4-7B from Diodes Incorporated is a fixed 4.5V, 150mA ultra-low quiescent current LDO regulator in X2-DFN1010-4 (Type B) package, featuring ±1% output voltage accuracy at +25°C, 0.5µA typical quiescent current, and 60dB PSRR at 1kHz - designed for power management in battery-constrained wearable and IoT sensor modules.

For engineers reviewing the AP7351D-45FS4-7B datasheet, AP7351D-45FS4-7B pinout, AP7351D-45FS4-7B application, or AP7351D-45FS4-7B equivalent, key selection criteria include dropout voltage at 150mA (0.14–0.35V), enable threshold compatibility (EN high ≥1.0V), thermal resistance (θ_JA = 237°C/W), and discharge functionality for fast VOUT decay during shutdown.

Technical Context

The AP7351D-45FS4-7B integrates a precision voltage reference, error amplifier, current-limit circuit, and active output discharge path. Its internal resistor network sets the fixed 4.5V output without external feedback components.

Enable control is implemented via a dedicated EN pin with defined logic thresholds (V_EN(H) ≥1.0V, V_EN(L) ≤0.4V); the device enters shutdown with I_STANDBY as low as 0.02µA and activates discharge resistance (~35Ω) when EN is pulled low.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 4.5V ±1% at +25°C; ensures stable rail for 3.3V/5V-compatible peripherals requiring tight regulation.
Max Output Current	150mA continuous; supports moderate-power sensors, BLE radios, and microcontroller peripherals without thermal derating in X2-DFN1010-4.
Quiescent Current	0.5µA typical; extends battery life in always-on wearables by minimizing standby drain.
Dropout Voltage	0.14V (min) to 0.35V (max) at 150mA; enables operation down to VIN = 4.64V, critical for single-cell Li-ion or coin-cell applications.
PSRR	60dB at 1kHz; suppresses switching noise from upstream DC-DC converters feeding the LDO input.
Enable Threshold	V_EN(H) ≥1.0V, V_EN(L) ≤0.4V; compatible with 1.8V/3.3V GPIOs without level-shifting.
Thermal Resistance	θ_JA = 237°C/W (X2-DFN1010-4); requires minimal PCB copper area for thermal relief in space-constrained layouts.

Pinout & Package

X2-DFN1010-4 (Type B) is a 1.0mm × 1.0mm, 0.4mm pitch, 4-terminal surface-mount package with exposed thermal pad (EP). The EP must be connected to GND or large copper pour for optimal thermal performance.

Pin/Terminal	Circuit Role	Design Meaning
PIN1 (Top View)	VOUT	Regulated 4.5V output; connects directly to load and local 0.1µF ceramic capacitor.
PIN2 (Top View)	GND	Analog/digital ground reference; must be low-impedance connection to PCB ground plane.
PIN3 (Top View)	EN	Active-high enable; floating state is prohibited; ties to VIN for always-on operation.
PIN4 (Top View)	VIN	Input supply (1.4–5.5V); requires 0.1µF ceramic decoupling capacitor placed adjacent to pin.
EP (Bottom)	Exposed Pad	Thermal interface only; not electrically functional as GND unless explicitly connected externally.

Key Features

Feature	Design Value
Ultra-low quiescent current	0.5µA typical enables >1-year battery life in 10µA average-current wearable devices.
Active output discharge	~35Ω internal discharge path pulls VOUT to GND within microseconds after EN deactivation, preventing floating rails.
Wide input range	1.4V to 5.5V supports single alkaline, Li-ion, or USB-supplied systems without input pre-regulation.
High PSRR at 1kHz	60dB attenuation of ripple from noisy switchers ensures clean analog sensor or RF power supply rails.
±1% output accuracy	Tight regulation meets ADC reference and MCU core voltage tolerance requirements without calibration.

Applications

Wearable Fitness Tracker

IoT Environmental Sensor Node

Use Scenario: Continuous heart-rate monitoring using optical sensor and BLE SoC powered by CR2032 coin cell.

IC Role / Device Role / Timing Role: Primary 4.5V LDO supplying analog front-end and radio transceiver; enables low-duty-cycle wake-up with sub-µA sleep current.

Use Value: 0.02µA standby current extends battery life to 18+ months; 4.5V output matches BLE IC VDDIO requirements without external level shifters.

Use Scenario: Battery-powered temperature/humidity node transmitting data every 5 minutes via LoRaWAN.

IC Role / Device Role / Timing Role: Power source for MCU, sensor IC, and RF transceiver; regulated rail ensures consistent ADC conversion and RF transmit power.

Use Value: 60dB PSRR prevents switching noise from LoRa PA from corrupting sensor readings; 150mA headroom supports burst transmit current.

Wireless Camera Module

Medical Patch Monitor

Use Scenario: Miniaturized HD camera module in smart glasses with motion-triggered recording.

IC Role / Device Role / Timing Role: Stable 4.5V supply for image sensor and video encoder; fast enable/disable synchronizes with motion detection logic.

Use Value: Enable turn-on time <100µs ensures no frame loss at wake-up; active discharge prevents residual charge from interfering with next boot sequence.

Use Scenario: Disposable ECG patch operating for 7 days on a single button cell.

IC Role / Device Role / Timing Role: Critical power regulator for ultra-low-power analog signal chain and Bluetooth LE transmitter.

Use Value: ±1% output accuracy maintains ECG amplifier gain stability across temperature; 0.14V dropout allows operation until battery reaches 4.64V.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MCP1700T-4502E/TT	No active output discharge; 1.6µA quiescent current; SOT-23-5 package.	Lacks fast VOUT decay; higher IQ reduces battery life in deep-sleep systems.	Select if discharge function is unnecessary and board space permits larger SOT-23-5 footprint.
TPS78045QDSERQ1	AEC-Q100 qualified; 0.5µA IQ; 0.2V dropout at 150mA; WSON-6 package.	Automotive-grade qualification adds cost and lead time; lower dropout suits tighter VIN margins.	Choose only for automotive programs requiring PPAP and IATF 16949 compliance.

Compared with MCP1700T-4502E/TT, AP7351D-45FS4-7B delivers 3× lower quiescent current and integrated discharge for faster system reset; versus TPS78045QDSERQ1, it offers smaller footprint and lower cost but lacks automotive qualification and has higher dropout.

Availability

AP7351D-45FS4-7B is available at Aetrix Electronics and suitable for wearable electronics, IoT sensor nodes, wireless camera modules, and medical patch monitors requiring stable component supply with guaranteed long-term availability.

Supply support for AP7351D-45FS4-7B 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 manufacturer specializing in discrete, analog, and mixed-signal solutions for power management, signal integrity, and connectivity applications.

The AP7351D belongs to Diodes' ultra-low-I_Q LDO family, engineered specifically for extended-battery-life portable and edge-sensing devices where micropower efficiency and small form factor are critical.

FAQ

What is the minimum input voltage required for AP7351D-45FS4-7B to maintain regulation at full 150mA load?

The minimum input voltage is determined by dropout: at 150mA, worst-case dropout is 0.35V, so VIN must be ≥4.85V to sustain 4.5V output. At lighter loads (e.g., 1mA), dropout drops to ~0.14V, allowing VIN as low as 4.64V while maintaining regulation.

Can the EN pin be left unconnected, or does it require a pull-up/down resistor?

The EN pin must never be left floating. It requires either a direct connection to VIN (for always-on operation) or a controlled GPIO signal. If unused, tie EN to VIN with a 100kΩ resistor; a floating EN may cause erratic enable/disable behavior due to noise coupling.

Does the AP7351D-45FS4-7B require an output capacitor, and what type is recommended?

Yes - a minimum 0.1µF ceramic capacitor (X5R/X7R) is required between VOUT and GND for stability and transient response. Larger values (e.g., 1–10µF) improve load-step immunity. Low-ESR ceramics are mandatory; tantalum or aluminum electrolytics are not recommended due to ESR-related instability.

How does the active output discharge function behave during shutdown?

When EN is pulled low, the internal ~35Ω discharge path connects VOUT to GND, discharging the output capacitor rapidly. For a 1µF COUT, VOUT falls from 4.5V to <100mV in <50µs. This prevents back-powering of upstream circuitry and ensures deterministic power sequencing in multi-rail systems.

AP7351D-45FS4-7B Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: 4-XDFN Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Active

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 5.5V

Voltage - Output (Min/Fixed):: 4.5V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.35V @ 150mA

Current - Output:: 150mA

Current - Quiescent (Iq):: 1 µA

Current - Supply (Max):: -

PSRR:: 60dB (1kHz)

Control Features:: Current Limit, Enable

Protection Features:: Over Current

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

Grade:: Automotive

Qualification:: AEC-Q100

Mounting Type:: Surface Mount

Supplier Device Package:: X2-DFN1010-4 (Type B)

AP7351D-45FS4-7B FAQ

1.How can I place an order for AP7351D-45FS4-7B through Aetrix?

Please submit a Request for Quotation (RFQ) for AP7351D-45FS4-7B 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 AP7351D-45FS4-7B reliable?

The price and inventory of AP7351D-45FS4-7B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AP7351D-45FS4-7B is usually 5 days.

3.What payment methods are accepted for AP7351D-45FS4-7B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AP7351D-45FS4-7B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AP7351D-45FS4-7B?

AP7351D-45FS4-7B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AP7351D-45FS4-7B 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 AP7351D-45FS4-7B?

For technical support, including AP7351D-45FS4-7B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AP7351D-45FS4-7B requirements.

6.How does Aetrix verify that AP7351D-45FS4-7B is sourced from the original manufacturer or authorized distributors?

All AP7351D-45FS4-7B 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 AP7351D-45FS4-7B meets industry standards.

7.What is the process for return or replacement of AP7351D-45FS4-7B?

All AP7351D-45FS4-7B units undergo pre-shipment inspection (PSI). If there is an issue with AP7351D-45FS4-7B, 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 AP7351D-45FS4-7B part is unused and in its original packaging.

Return procedure for AP7351D-45FS4-7B:

1.Submit a request within 90 days.

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

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