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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

onsemi FAN53611AUC205X

Name: FAN53611AUC205X
Brand: onsemi
SKU: FAN53611AUC205X
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FAN53611AUC205X

Manufacturer:: onsemi

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 6-UFBGA, WLCSP

Datasheet:: FAN53611AUC205X.pdf

Description:: IC REG BUCK 2.05V 1A 6WLCSP

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Product details

Overview

FAN53611AUC205X from onsemi is a 6 MHz, 1 A synchronous buck regulator in WLCSP-6 package delivering a fixed 2.050 V output from 2.3 V–5.5 V input. It features 24 µA quiescent current in PFM mode, internal soft-start, input UVLO (2.27 V), thermal shutdown (150°C), and optional active output discharge (230 Ω). It targets space-constrained portable power rails for application processors and RF modules.

For engineers reviewing the FAN53611AUC205X datasheet, pinout, applications, or equivalent options, key selection criteria include its 6 MHz fixed-frequency operation enabling ultra-small 470 nH inductors and 4.7 µF ceramic output capacitors, seamless PWM/PFM transition, and verified 92% peak efficiency at 1 A load.

Technical Context

The FAN53611AUC205X employs a proprietary non-linear fixed-frequency PWM modulator with synchronous rectification, maintaining 6 MHz switching across wide VIN (2.3–5.5 V) and IOUT (0–1 A) ranges. Its architecture eliminates ESR dependency, enabling stable regulation with low-ESR ceramic capacitors.

Control logic integrates MODE pin functionality for forced PWM, external clock synchronization (1.3–1.7 MHz input → 5.2–6.8 MHz sync), and automatic PFM entry below ~300 mA. Soft-start uses dual-slew-rate ramping (50 mV/µs to 1 V, then 12.5 mV/µs) with displacement-current limiting to prevent startup failure under large COUT.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 2.050 V ±3.7% (1.973–2.127 V) over full load and temperature range - ensures stable core voltage for 2.0 V–2.1 V I/O domains.
Max Output Current	1 A continuous - supports high-efficiency power delivery to application processors or RF transceivers without external current boosting.
Switching Frequency	6 MHz nominal (5.4–6.6 MHz) - enables use of 470 nH inductors and 4.7 µF output capacitors, minimizing PCB footprint.
Quiescent Current	24 µA typical in PFM mode - extends battery life in always-on subsystems such as sensor hubs or modem standby circuits.
Input Voltage Range	2.3 V to 5.5 V - compatible with single-cell Li-ion (2.7–4.2 V), USB VBUS (4.75–5.25 V), and regulated 3.3 V/5 V rails.
UVLO Threshold	2.27 V rising, 200 mV hysteresis - prevents erratic startup/shutdown during brownout conditions in portable systems.
Thermal Shutdown	150°C activation with 15°C hysteresis - protects die integrity during sustained overload or poor thermal layout without latch-up.

Pinout & Package

Package: 6-bump Wafer-Level Chip-Scale Package (WLCSP), 0.4 mm pitch, 1.16 mm × 0.86 mm footprint, 586 µm typical height. Bumps face down in standard mounting orientation.

Pin/Terminal	Circuit Role	Design Meaning
A1	MODE	Configures operating mode: logic high forces PWM; logic low enables auto PFM/PWM transition; also accepts 1.3–1.7 MHz sync signal (×4 output).
B1	SW	Switching node - connects directly to inductor; carries high di/dt pulsed current; requires short, low-inductance trace routing.
C1	FB	Feedback input - senses output voltage; internal resistor divider sets 2.050 V; no external resistors required.
C2	GND	Power and signal ground - must be connected to solid ground plane; serves as reference for all analog and power circuits.
B2	EN	Enable control - active high (>1.2 V); <0.4 V disables regulator and activates optional output discharge path (230 Ω to GND).
A2	VIN	Main power input - supplies internal circuitry and high-side switch; requires local 2.2 µF ceramic capacitor placed adjacent to pin.

Key Features

Feature	Design Value
6 MHz fixed-frequency PWM + auto PFM	Enables smallest possible passive components while maintaining <15 mVpp ripple at light loads and fast transient response (<10 µs recovery from 10–200 mA step).
Internal soft-start with slew-rate control	Prevents inrush current and output overshoot via controlled 50 mV/µs (0–1 V) and 12.5 mV/µs (1 V–2.05 V) ramp - eliminates need for external timing components.
Active output discharge (enabled)	230 Ω internal path discharges FB node to GND when EN = LOW - ensures rapid, safe output collapse for sequencing-critical subsystems.
Synchronous rectification with low RDS(on)	175 mΩ PMOS / 165 mΩ NMOS switches deliver >92% peak efficiency and maintain >80% efficiency down to 1 mA load.
Robust protection suite	Includes cycle-by-cycle current limit (1750 mA typ), thermal shutdown (150°C), UVLO (2.27 V), and hiccup-mode fault recovery - reduces system-level safety margin requirements.

Applications

Mobile Application Processor Core Rail	Wi-Fi/Bluetooth SoC I/O Supply
Use Scenario: Powering ARM Cortex-A series CPU cores requiring tightly regulated 2.05 V at up to 1 A with minimal voltage deviation during burst activity. IC Role / Device Role / Timing Role: Primary DC-DC converter providing dynamically scaled core voltage; operates in PWM mode during active compute, transitions to PFM in idle states. Use Value: 6 MHz switching minimizes inductor size (470 nH) and avoids audible noise; 24 µA quiescent current extends battery runtime in suspend-to-RAM states.	Use Scenario: Supplying clean, low-noise 2.05 V to Wi-Fi 6/Bluetooth 5.0 combo chips in smartphones and wearables. IC Role / Device Role / Timing Role: Dedicated point-of-load regulator with integrated soft-start and output discharge for precise power sequencing with baseband processor. Use Value: Active discharge (230 Ω) ensures sub-100 µs output collapse, meeting strict reset timing requirements between radio modes.
Ultra-Thin Tablet System-on-Chip (SoC) Rail	Portable Medical Sensor Hub Power
Use Scenario: Delivering 2.05 V at up to 1 A to application SoCs in sub-8 mm thick tablets where board area and thermal headroom are severely constrained. IC Role / Device Role / Timing Role: High-density power solution using WLCSP-6 package (1.16 mm × 0.86 mm) with no external feedback resistors. Use Value: 586 µm profile and 0.4 mm bump pitch enable direct placement under SoC; 125 °C/W θJA allows 1 A operation on 2-layer boards.	Use Scenario: Powering low-power MCU + analog front-end (AFE) in battery-operated wearable ECG/SpO₂ monitors requiring long-term stability and low EMI. IC Role / Device Role / Timing Role: Primary regulator with best-in-class light-load efficiency and low output ripple (<12 mVpp at 10 mA) to minimize sensor noise coupling. Use Value: PFM mode maintains >85% efficiency at 100 µA load; 6 MHz frequency places switching harmonics beyond sensitive analog bands (≥30 MHz).

Mobile Application Processor Core Rail

Wi-Fi/Bluetooth SoC I/O Supply

Use Scenario: Powering ARM Cortex-A series CPU cores requiring tightly regulated 2.05 V at up to 1 A with minimal voltage deviation during burst activity.

IC Role / Device Role / Timing Role: Primary DC-DC converter providing dynamically scaled core voltage; operates in PWM mode during active compute, transitions to PFM in idle states.

Use Value: 6 MHz switching minimizes inductor size (470 nH) and avoids audible noise; 24 µA quiescent current extends battery runtime in suspend-to-RAM states.

Use Scenario: Supplying clean, low-noise 2.05 V to Wi-Fi 6/Bluetooth 5.0 combo chips in smartphones and wearables.

IC Role / Device Role / Timing Role: Dedicated point-of-load regulator with integrated soft-start and output discharge for precise power sequencing with baseband processor.

Use Value: Active discharge (230 Ω) ensures sub-100 µs output collapse, meeting strict reset timing requirements between radio modes.

Ultra-Thin Tablet System-on-Chip (SoC) Rail

Portable Medical Sensor Hub Power

Use Scenario: Delivering 2.05 V at up to 1 A to application SoCs in sub-8 mm thick tablets where board area and thermal headroom are severely constrained.

IC Role / Device Role / Timing Role: High-density power solution using WLCSP-6 package (1.16 mm × 0.86 mm) with no external feedback resistors.

Use Value: 586 µm profile and 0.4 mm bump pitch enable direct placement under SoC; 125 °C/W θJA allows 1 A operation on 2-layer boards.

Use Scenario: Powering low-power MCU + analog front-end (AFE) in battery-operated wearable ECG/SpO₂ monitors requiring long-term stability and low EMI.

IC Role / Device Role / Timing Role: Primary regulator with best-in-class light-load efficiency and low output ripple (<12 mVpp at 10 mA) to minimize sensor noise coupling.

Use Value: PFM mode maintains >85% efficiency at 100 µA load; 6 MHz frequency places switching harmonics beyond sensitive analog bands (≥30 MHz).

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TPS62260DRVR	Fixed 2.05 V output, 600 mA max, 2.25 MHz switching, 22 µA IQ - lower current rating and slower frequency limits inductor/capacitor miniaturization.	Targeted at lower-power MCUs and sensors; not suitable for 1 A processor cores or RF transceivers.	Select only if load never exceeds 600 mA and board space allows larger 1 µH inductor and 10 µF output capacitor.
MP2155GQZ-P	Adjustable output (0.6–5.5 V), 1 A, 2.2 MHz, 25 µA IQ, no integrated discharge - requires external feedback resistors and lacks active discharge path.	Used where output voltage flexibility or sequencing with multiple rails is needed; unsuitable for fixed-voltage, discharge-critical designs.	Choose when design requires programmable VOUT or multi-rail coordination; avoid when footprint, simplicity, or guaranteed 2.05 V discharge behavior are mandatory.

Compared with TPS62260DRVR and MP2155GQZ-P, the FAN53611AUC205X delivers higher current (1 A vs. 600 mA/1 A), faster switching (6 MHz vs. 2.25/2.2 MHz), and built-in active discharge - making it uniquely suited for compact, high-performance mobile SoC rails demanding fixed 2.05 V with strict sequencing.

Availability

FAN53611AUC205X is available at Aetrix Electronics and suitable for mobile application processor core rails, Wi-Fi/Bluetooth SoC I/O supplies, and ultra-thin tablet SoC power delivery requiring stable component supply, tight voltage accuracy, and long-lifecycle support.

Supply support for FAN53611AUC205X 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

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

The FAN53611AUC205X belongs to the FAN536xx family of high-frequency synchronous buck regulators designed specifically for space-constrained portable electronics requiring ultra-small passives, low quiescent current, and robust protection in WLCSP packaging.

FAQ

What is the output voltage tolerance of the FAN53611AUC205X over temperature and load?

The FAN53611AUC205X delivers a fixed 2.050 V output with ±3.7% accuracy (1.973 V to 2.127 V) across full operating conditions: 0–1 A load, −40°C to +85°C ambient, and 2.7 V–5.5 V input. In PWM mode specifically, tolerance tightens to ±2.3% (2.004 V–2.096 V), supporting precision voltage domains for modern application processors. This specification is validated per the official onsemi datasheet Rev. 2.

Does the FAN53611AUC205X require external feedback resistors?

No, the FAN53611AUC205X does not require external feedback resistors. It integrates an internal resistor divider calibrated for a precise 2.050 V output. The FB pin (C1) connects directly to the output capacitor node, eliminating component count, layout sensitivity, and resistor tolerance errors - a key advantage for high-volume portable designs where bill-of-materials simplification is critical.

How does the MODE pin function on the FAN53611AUC205X?

The MODE pin (A1) on the FAN53611AUC205X provides three functions: logic high (>1.2 V) forces continuous PWM operation; logic low (<0.4 V) enables automatic PFM/PWM transition based on load; and a 1.3–1.7 MHz square wave input synchronizes the internal 6 MHz oscillator to 5.2–6.8 MHz. The pin includes Schmitt-trigger buffering to tolerate slow edges, and must never be left floating per the datasheet.

What protection features are integrated into the FAN53611AUC205X?

The FAN53611AUC205X integrates cycle-by-cycle overcurrent protection (1750 mA typical limit), thermal shutdown (150°C activation with 15°C hysteresis), input under-voltage lockout (2.27 V rising threshold), and hiccup-mode fault recovery. It also supports optional active output discharge (230 Ω to GND when EN = LOW), which is enabled in the FAN53611AUC205X variant per the ordering table.

Can the FAN53611AUC205X operate with a 2.3 V input supply at full 1 A load?

Yes, the FAN53611AUC205X supports 2.3 V minimum input and delivers full 1 A output at 2.05 V across the specified temperature range. However, at VIN = 2.3 V and high load, switching frequency may drop below 6 MHz due to minimum off-time constraints - confirmed in Figure 34 of the datasheet. For guaranteed 6 MHz operation at 1 A, VIN ≥ 2.7 V is recommended.

FAN53611AUC205X Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: 6-UFBGA, WLCSP

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Fixed

Number of Outputs:: 1

Voltage - Input (Min):: 2.3V

Voltage - Input (Max):: 5.5V

Voltage - Output (Min/Fixed):: 2.05V

Voltage - Output (Max):: -

Current - Output:: 1A

Frequency - Switching:: 6MHz

Synchronous Rectifier:: Yes

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 6-WLCSP (1.23x0.88)

FAN53611AUC205X FAQ

1.How can I place an order for FAN53611AUC205X through Aetrix?

Please submit a Request for Quotation (RFQ) for FAN53611AUC205X 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 FAN53611AUC205X reliable?

The price and inventory of FAN53611AUC205X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN53611AUC205X is usually 5 days.

3.What payment methods are accepted for FAN53611AUC205X?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN53611AUC205X transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FAN53611AUC205X?

FAN53611AUC205X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FAN53611AUC205X 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 FAN53611AUC205X?

For technical support, including FAN53611AUC205X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN53611AUC205X requirements.

6.How does Aetrix verify that FAN53611AUC205X is sourced from the original manufacturer or authorized distributors?

All FAN53611AUC205X 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 FAN53611AUC205X meets industry standards.

7.What is the process for return or replacement of FAN53611AUC205X?

All FAN53611AUC205X units undergo pre-shipment inspection (PSI). If there is an issue with FAN53611AUC205X, 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 FAN53611AUC205X part is unused and in its original packaging.

Return procedure for FAN53611AUC205X:

1.Submit a request within 90 days.

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

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