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

onsemi FAN25800AUC33X

Name: FAN25800AUC33X
Brand: onsemi
SKU: FAN25800AUC33X
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FAN25800AUC33X

Manufacturer:: onsemi

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

Package:: 4-XFBGA, WLCSP

Datasheet:: FAN25800AUC33X.pdf

Description:: IC REG LINEAR 3.3V 500MA 4WLCSP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

FAN25800AUC33X from ON Semiconductor is a 3.3 V, 500 mA low-noise, low-quiescent-current LDO regulator in a 4-ball WLCSP package. It delivers ultra-low output noise (8 µV_RMS, 10 Hz–100 kHz), high PSRR (85 dB at 100 Hz), and <70 mV dropout at 250 mA - optimized for powering RF-sensitive circuits such as WiFi modules and smartphone baseband processors.

For engineers reviewing the FAN25800AUC33X datasheet, pinout, applications, or equivalent options, key selection criteria include its 17 µA quiescent current in regulation, stability with 1.5 µF 0201 ceramic capacitors, thermal shutdown and UVLO protection, and compatibility with space-constrained portable designs requiring clean, efficient post-DC-DC regulation.

Technical Context

The FAN25800AUC33X employs a PMOS pass transistor architecture enabling low dropout and near-zero gate-drive current, supporting stable operation across 2.3 V to 5.5 V input range. Its internal bandgap reference and error amplifier deliver ±1.9% output voltage accuracy over load (5–500 mA) and temperature (−40°C to +85°C).

Soft-start control limits inrush current during enable transitions, while integrated short-circuit protection clamps output current to 550–800 mA and thermal shutdown activates at 150°C with 20°C hysteresis - ensuring robustness in transient-loaded portable systems without external supervision circuitry.

Key Specifications

Parameter	Value and Actual Design Meaning
V_OUT	3.3 V ±1.9% - tightly regulated output suitable for powering 3.3 V I/O rails and RF ICs without additional filtering.
I_OUT Max	500 mA - sufficient for baseband processors, WiFi/BT SoCs, and sensor hubs in compact handheld devices.
Dropout Voltage	<70 mV at 250 mA - enables high efficiency even at low VIN–VOUT differentials (e.g., 3.6 V → 3.3 V).
Output Noise	8 µV_RMS (10 Hz–100 kHz) - minimizes phase noise in local oscillators and jitter in ADC clocking paths.
PSRR	85 dB at 100 Hz - suppresses switching ripple from upstream DC-DC converters in hybrid power architectures.
I_Q	17 µA in regulation - extends battery life in always-on subsystems like RTC or wake-up controllers.
Package	4-ball WLCSP, 0.65 mm × 0.65 mm, 0.35 mm pitch - enables placement directly beneath BGA processors to minimize trace inductance.

Pinout & Package

Package: 4-ball Wafer-Level Chip-Scale Package (WLCSP), 0.65 mm × 0.65 mm footprint, 0.35 mm ball pitch, plated solder bumps, max 330 µm thickness.

Pin/Terminal	Circuit Role	Design Meaning
A1 (VIN)	Input power supply connection	Accepts 2.3–5.5 V input; requires local 1.5 µF 0201 ceramic capacitor for stability and EMI suppression.
A2 (VOUT)	Regulated output node	Delivers 3.3 V ±1.9% at up to 500 mA; supports dual 1.5 µF 0201 output caps for optimal noise performance.
B1 (EN)	Active-high enable control	Logic-compatible with 1.05–1.8 V high-level drive; must not float; enables soft-start and sub-1 µA shutdown current.
B2 (GND)	Power and signal reference ground	Single-point ground return for VIN, VOUT, and EN; requires direct low-inductance connection to PCB ground plane.

Key Features

Feature	Design Value
Low-noise regulation	8 µV_RMS integrated noise (10 Hz–100 kHz) enables clean power for RF transceivers and high-resolution ADCs.
Ultra-low I_Q	17 µA operating current allows multi-week battery runtime in always-on sensor nodes and wearables.
Small-footprint stability	Stable with two 1.5 µF, 0201-case ceramic capacitors - eliminates need for larger 0402/0603 parts in dense layouts.
Integrated protection	Thermal shutdown (150°C), UVLO (2.1–2.3 V), and short-circuit current limiting (550–800 mA) reduce external component count.
Controlled startup	Soft-start limits inrush current to prevent input rail sag and avoids false triggering of upstream power monitors.

Applications

WiFi Module Power	Smartphone Baseband Rail
Use Scenario: Powering 2.4 GHz/5 GHz WiFi SoC RF sections and analog front-end circuitry. IC Role / Device Role / Timing Role: Post-regulator cleaning switching noise from buck converter outputs feeding RF synthesizers and LNA bias networks. Use Value: 85 dB PSRR at 100 Hz and 8 µV_RMS noise prevent EVM degradation and adjacent-channel leakage in 802.11ac/ax transmission.	Use Scenario: Supplying core voltage to application processor I/O banks and memory interfaces in smartphones. IC Role / Device Role / Timing Role: Low-dropout, fast-transient LDO delivering stable 3.3 V under dynamic load steps (10 → 250 mA in 400 ns). Use Value: <70 mV dropout and 250 µs startup time support rapid power-state transitions without brownout or reset events.
Portable Medical Sensor Hub	Bluetooth LE Wearable Subsystem
Use Scenario: Powering ultra-low-power biosensor signal chains (ECG, SpO₂) in FDA-compliant wearable patches. IC Role / Device Role / Timing Role: Primary analog rail regulator with sub-20 µA quiescent current and medical-grade noise immunity. Use Value: 17 µA I_Q and 8 µV_RMS noise ensure >10-day battery life and <1 LSB noise floor in 24-bit delta-sigma ADCs.	Use Scenario: Supplying BLE radio and microcontroller peripherals in coin-cell-powered earbuds and trackers. IC Role / Device Role / Timing Role: Enable-controlled LDO enabling deep-sleep mode with <1 µA shutdown current and fast wake-up. Use Value: EN pin logic compatibility (1.05 V VIH) allows direct interface with 1.8 V MCU GPIOs; 500 µs startup ensures responsive connection establishment.

WiFi Module Power

Smartphone Baseband Rail

Use Scenario: Powering 2.4 GHz/5 GHz WiFi SoC RF sections and analog front-end circuitry.

IC Role / Device Role / Timing Role: Post-regulator cleaning switching noise from buck converter outputs feeding RF synthesizers and LNA bias networks.

Use Value: 85 dB PSRR at 100 Hz and 8 µV_RMS noise prevent EVM degradation and adjacent-channel leakage in 802.11ac/ax transmission.

Use Scenario: Supplying core voltage to application processor I/O banks and memory interfaces in smartphones.

IC Role / Device Role / Timing Role: Low-dropout, fast-transient LDO delivering stable 3.3 V under dynamic load steps (10 → 250 mA in 400 ns).

Use Value: <70 mV dropout and 250 µs startup time support rapid power-state transitions without brownout or reset events.

Portable Medical Sensor Hub

Bluetooth LE Wearable Subsystem

Use Scenario: Powering ultra-low-power biosensor signal chains (ECG, SpO₂) in FDA-compliant wearable patches.

IC Role / Device Role / Timing Role: Primary analog rail regulator with sub-20 µA quiescent current and medical-grade noise immunity.

Use Value: 17 µA I_Q and 8 µV_RMS noise ensure >10-day battery life and <1 LSB noise floor in 24-bit delta-sigma ADCs.

Use Scenario: Supplying BLE radio and microcontroller peripherals in coin-cell-powered earbuds and trackers.

IC Role / Device Role / Timing Role: Enable-controlled LDO enabling deep-sleep mode with <1 µA shutdown current and fast wake-up.

Use Value: EN pin logic compatibility (1.05 V VIH) allows direct interface with 1.8 V MCU GPIOs; 500 µs startup ensures responsive connection establishment.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
Torex XC6210B332MR-G	3.3 V, 500 mA, 25 µA I_Q, 15 µV_RMS noise, SOT-25 package (2.9 mm × 2.8 mm)	Larger footprint; higher noise; lacks UVLO and soft-start	Preferred where board area permits larger package and cost sensitivity outweighs noise/size requirements.
Richtek RT9080-33PU5	3.3 V, 500 mA, 20 µA I_Q, 12 µV_RMS noise, DFN-6 (1.2 mm × 1.2 mm)	6-pin DFN vs. 4-ball WLCSP; requires external bypass cap; no integrated short-circuit foldback	Selected when thermal dissipation demands larger copper pads or when existing layout accommodates DFN-6 footprints.

Compared with XC6210B332MR-G and RT9080-33PU5, the FAN25800AUC33X offers the smallest form factor (0.65 mm²), lowest noise (8 µV_RMS), and most comprehensive protection set - making it optimal for next-generation miniaturized RF and portable medical designs where size, noise, and reliability are co-prioritized.

Availability

FAN25800AUC33X is available at Aetrix Electronics and suitable for WiFi modules, smartphone baseband rails, and portable medical sensor hubs requiring stable component supply, consistent parametric performance, and long-term lifecycle support.

Supply support for FAN25800AUC33X 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The FAN25800 series was developed by Fairchild Semiconductor (now part of ON Semiconductor) to address noise-sensitive, space-constrained portable applications - specifically targeting post-DC-DC regulation in RF and high-resolution signal-chain systems.

FAQ

What is the maximum input voltage rating for the FAN25800AUC33X?

The FAN25800AUC33X has an absolute maximum input voltage (VIN) rating of 6.0 V with respect to GND. However, the recommended operating range is 2.3 V to 5.5 V. Exceeding 5.5 V may trigger UVLO or cause thermal stress, especially at full 500 mA load - always verify thermal design using θJA = 180°C/W when operating near upper limits.

Does the FAN25800AUC33X require external compensation components?

No, the FAN25800AUC33X is internally compensated and designed to be stable with minimal external capacitance: two 1.5 µF, 0201-size X5R ceramic capacitors (one on VIN, two on VOUT) meet all loop stability requirements. No series resistors, feedforward caps, or external compensation networks are needed - simplifying layout and reducing BOM count.

How does the enable (EN) pin behave during power-up?

The EN pin of the FAN25800AUC33X is active-high with VIH = 1.05 V minimum and VIL = 0.4 V maximum. It has no internal pull-down, so it must be actively driven or externally pulled high. When EN rises above VIH, the device initiates a controlled soft-start sequence - ramping VOUT over ~250–500 µs to limit inrush current and avoid input rail disturbance.

Can the FAN25800AUC33X be used with 1.0 µF input and output capacitors?

Yes - the FAN25800AUC33X is stable with 1.0 µF, 0201 ceramic capacitors on both VIN and VOUT (per Table 1 Note 3). This alternative reduces component count and cost while maintaining stability, though 1.5 µF is recommended for optimal PSRR and noise performance across temperature and bias conditions.

What thermal derating applies to the FAN25800AUC33X at 500 mA output?

At 500 mA and V_IN = 3.6 V, the FAN25800AUC33X dissipates ~150 mW. With θ_JA = 180°C/W, junction temperature rise is ~27°C above ambient. To stay within TJ(max) = 125°C, maximum ambient temperature must be ≤98°C - but derating is advised above 85°C ambient per datasheet limits. Use PCB copper pours and thermal vias to improve heat spreading in high-density layouts.

FAN25800AUC33X Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: 4-XFBGA, WLCSP

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):: 3.3V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.13V @ 250mA

Current - Output:: 500mA

Current - Quiescent (Iq):: 25 µA

Current - Supply (Max):: -

PSRR:: 85dB ~ 68dB (100Hz ~ 50Hz)

Control Features:: Enable

Protection Features:: Over Temperature, Short Circuit, Under Voltage Lockout (UVLO)

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 4-WLCSP (0.65x0.65)

FAN25800AUC33X FAQ

1.How can I place an order for FAN25800AUC33X through Aetrix?

Please submit a Request for Quotation (RFQ) for FAN25800AUC33X 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 FAN25800AUC33X reliable?

The price and inventory of FAN25800AUC33X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN25800AUC33X is usually 5 days.

3.What payment methods are accepted for FAN25800AUC33X?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN25800AUC33X transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FAN25800AUC33X?

FAN25800AUC33X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FAN25800AUC33X 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 FAN25800AUC33X?

For technical support, including FAN25800AUC33X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN25800AUC33X requirements.

6.How does Aetrix verify that FAN25800AUC33X is sourced from the original manufacturer or authorized distributors?

All FAN25800AUC33X 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 FAN25800AUC33X meets industry standards.

7.What is the process for return or replacement of FAN25800AUC33X?

All FAN25800AUC33X units undergo pre-shipment inspection (PSI). If there is an issue with FAN25800AUC33X, 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 FAN25800AUC33X part is unused and in its original packaging.

Return procedure for FAN25800AUC33X:

1.Submit a request within 90 days.

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

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