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

onsemi FAN53611UC123X

Name: FAN53611UC123X
Brand: onsemi
SKU: FAN53611UC123X
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FAN53611UC123X

Manufacturer:: onsemi

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 6-UFBGA, WLCSP

Datasheet:: FAN53611UC123X.pdf

Description:: IC REG BUCK 1.233V 1A 6WLCSP

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Product details

Overview

FAN53611UC123X from onsemi is a 6 MHz, 1 A synchronous buck regulator in WLCSP-6 package delivering fixed 1.233 V output from 2.3–5.5 V input. It features 24 µA quiescent current in PFM mode, internal soft-start, UVLO, thermal shutdown, and no active output discharge. It targets space-constrained portable power rails in tablets and data cards.

For engineers reviewing the FAN53611UC123X datasheet, pinout, applications, or equivalent options, key selection factors include its 1.233 V output accuracy (±4.2% over load/temperature), 6 MHz fixed-frequency operation enabling ultra-small 470 nH inductors, forced-PWM capability via MODE pin, and absence of active discharge - critical for systems requiring controlled VOUT decay during shutdown.

Technical Context

The FAN53611UC123X employs a proprietary non-linear fixed-frequency PWM modulator with seamless auto-transition between continuous conduction mode (CCM) and discontinuous conduction mode (DCM) PFM at light loads. Its switching node (SW) drives an external 470 nH inductor, while feedback (FB) senses output voltage directly at the 1.233 V rail.

Control is enabled via EN (active-high, 1.2 V threshold), with MODE pin supporting three functions: PFM/PWM selection (logic low/high), external clock synchronization (1.3–1.7 MHz square wave → 5.2–6.8 MHz sync), and Schmitt-triggered input tolerance. Internal 175 mΩ PMOS and 165 mΩ NMOS switches enable peak efficiency of 92% and >80% efficiency down to 1 mA load.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 1.233 V ±4.2% (1.185–1.281 V) across 0–1 A load and –40°C to +85°C ambient.
Max Output Current	1 A DC, supported by open-loop peak current limit of 1.5–2.0 A and thermal shutdown at 150°C.
Switching Frequency	6 MHz nominal fixed frequency; maintains regulation down to VIN = 2.7 V at high load; drops below 6 MHz when VIN < 2.7 V due to t_OFF(MIN) = 40 ns constraint.
Quiescent Current	24 µA typical in PFM mode (no load, AUTO); 8 mA in forced PWM mode; <1 µA in shutdown (EN = GND).
Input Voltage Range	2.3 V to 5.5 V operational; absolute max 7.0 V; UVLO activates at 2.27 V rising edge with 200 mV hysteresis.
Efficiency	Peak 92% at mid-load; >80% maintained from 1 mA to full 1 A load; optimized for ceramic output capacitors (4.7 µF min).
Package	6-bump Wafer-Level Chip-Scale Package (WLCSP), 0.4 mm pitch, 1.16 × 0.86 mm footprint, 547–625 µm height.

Pinout & Package

Package: 6-bump WLCSP (0.4 mm pitch), bottom-side bump layout with bumps facing down in standard mounting. Dimensions: 1.160 mm × 0.860 mm × 0.586 mm (typ). Land pattern uses NSMD pads (Ø0.260 mm copper, Ø0.300 mm solder mask opening).

Pin/Terminal	Circuit Role	Design Meaning
A1	MODE	Configures operating mode: logic 0 enables auto PFM/PWM transition; logic 1 forces PWM-only; 1.3–1.7 MHz square wave synchronizes switching to 4× frequency.
B1	SW	Switching node connecting to inductor; carries high di/dt pulsed current; requires low-inductance PCB routing to minimize EMI and voltage spikes.
C1	FB	Feedback input tied directly to output capacitor; sets regulated 1.233 V output; no external resistor divider required.
C2	GND	Power and signal ground reference; must be connected to low-impedance ground plane adjacent to CIN/COUT common point.
B2	EN	Enable input: >1.2 V enables regulation with soft-start; <0.4 V disables device and reduces supply current to <1 µA.
A2	VIN	Main input power supply (2.3–5.5 V); requires 2.2 µF ceramic capacitor placed within 2 mm of this pin and GND.

Key Features

Feature	Design Value
Ultra-high switching frequency	6 MHz operation allows use of 470 nH inductors and 4.7 µF output capacitors - reducing solution size by >50% vs. 1–2 MHz buck regulators.
Low-quiescent-current PFM mode	24 µA IQ preserves battery life in always-on subsystems while maintaining fast transient response (<100 ns edge recovery shown in load transients).
Integrated soft-start	Fixed slew-rate startup (50 mV/µs to 1 V, then 12.5 mV/µs) prevents inrush current and output overshoot; eliminates need for external timing components.
Synchronous rectification	Internal 175 mΩ PMOS / 165 mΩ NMOS switches eliminate external diode, enabling >92% peak efficiency and eliminating reverse recovery losses.
Robust protection suite	Includes cycle-by-cycle current limiting, thermal shutdown (150°C, 15°C hysteresis), UVLO, and fault restart - enabling reliable operation under overload or short-circuit conditions.

Applications

Mobile Data Card Power	Tablet Core Rail
Use Scenario: Powering baseband processor I/O or RF front-end in compact 3G/4G/WiFi data cards where board area is constrained and thermal dissipation is limited. IC Role / Device Role / Timing Role: Primary 1.233 V point-of-load regulator delivering up to 1 A with minimal external components (inductor + 2 caps). Use Value: 6 MHz switching enables tiny 0201-size 470 nH inductors and 0402 4.7 µF ceramics, reducing total solution footprint to <3 mm² while sustaining >85% efficiency at 500 mA.	Use Scenario: Supplying low-voltage logic rails (e.g., GPU or display interface cores) in thin-profile tablets requiring rapid load transient response and low standby power. IC Role / Device Role / Timing Role: High-efficiency synchronous buck converter with auto PFM/PWM mode switching to maintain >80% efficiency from 1 mA to full load. Use Value: 24 µA quiescent current extends battery runtime in sleep states; seamless PFM→PWM transition ensures <10 mV output deviation during 10–200–10 mA load steps (Figure 18).
Ultra-Mobile PC SoC I/O	DSC/DVC Image Sensor Bias
Use Scenario: Generating stable 1.233 V supply for I/O domains of Intel Atom or ARM-based ultra-mobile PCs where EMI sensitivity and thermal limits restrict inductor selection. IC Role / Device Role / Timing Role: Fixed-frequency 6 MHz buck regulator synchronized to system clock via MODE pin to avoid beat frequencies in noise-sensitive analog sections. Use Value: External clock synchronization (1.3–1.7 MHz input → 5.2–6.8 MHz output) eliminates switching noise peaks in narrowband receivers and improves PSRR by >10 dB at 1–10 MHz.	Use Scenario: Biasing CMOS image sensor analog front-end in digital still/video cameras where low-noise, ripple-free supply is critical for SNR preservation. IC Role / Device Role / Timing Role: Low-ripple PFM-mode regulator with optional forced PWM for noise-sensitive periods; no active discharge avoids uncontrolled VOUT collapse during idle. Use Value: Absence of active discharge (FAN53611UC123X variant) prevents unintended sensor reset during brief power-down sequences; output ripple <15 mV_pp at 200 mA (Figure 16).

Mobile Data Card Power

Tablet Core Rail

Use Scenario: Powering baseband processor I/O or RF front-end in compact 3G/4G/WiFi data cards where board area is constrained and thermal dissipation is limited.

IC Role / Device Role / Timing Role: Primary 1.233 V point-of-load regulator delivering up to 1 A with minimal external components (inductor + 2 caps).

Use Value: 6 MHz switching enables tiny 0201-size 470 nH inductors and 0402 4.7 µF ceramics, reducing total solution footprint to <3 mm² while sustaining >85% efficiency at 500 mA.

Use Scenario: Supplying low-voltage logic rails (e.g., GPU or display interface cores) in thin-profile tablets requiring rapid load transient response and low standby power.

IC Role / Device Role / Timing Role: High-efficiency synchronous buck converter with auto PFM/PWM mode switching to maintain >80% efficiency from 1 mA to full load.

Use Value: 24 µA quiescent current extends battery runtime in sleep states; seamless PFM→PWM transition ensures <10 mV output deviation during 10–200–10 mA load steps (Figure 18).

Ultra-Mobile PC SoC I/O

DSC/DVC Image Sensor Bias

Use Scenario: Generating stable 1.233 V supply for I/O domains of Intel Atom or ARM-based ultra-mobile PCs where EMI sensitivity and thermal limits restrict inductor selection.

IC Role / Device Role / Timing Role: Fixed-frequency 6 MHz buck regulator synchronized to system clock via MODE pin to avoid beat frequencies in noise-sensitive analog sections.

Use Value: External clock synchronization (1.3–1.7 MHz input → 5.2–6.8 MHz output) eliminates switching noise peaks in narrowband receivers and improves PSRR by >10 dB at 1–10 MHz.

Use Scenario: Biasing CMOS image sensor analog front-end in digital still/video cameras where low-noise, ripple-free supply is critical for SNR preservation.

IC Role / Device Role / Timing Role: Low-ripple PFM-mode regulator with optional forced PWM for noise-sensitive periods; no active discharge avoids uncontrolled VOUT collapse during idle.

Use Value: Absence of active discharge (FAN53611UC123X variant) prevents unintended sensor reset during brief power-down sequences; output ripple <15 mV_pp at 200 mA (Figure 16).

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	1.2 V fixed output (±1.5%), 600 mA max, 2.05–6.0 V input, 2.25 MHz switching, 17 µA IQ, no MODE pin sync.	Lacks external clock sync and 1 A capability; better suited for lower-current, cost-sensitive designs where 6 MHz size advantage is unnecessary.	Select TPS62260DRVR only if 600 mA suffices and 2.25 MHz operation is acceptable for larger inductor/capacitor sizing.
MP2143GJ-Z	1.2 V fixed output (±2%), 1.2 A max, 2.5–5.5 V input, 3 MHz switching, 30 µA IQ, no PFM/PWM select pin.	Higher IQ and no MODE control limits light-load efficiency tuning; 3 MHz requires ~2× larger inductor (1 µH) than FAN53611UC123X's 470 nH.	Choose MP2143GJ-Z only when wider input range (2.5–5.5 V) is mandatory and board area constraints are less severe than for mobile data cards.

Compared with TPS62260DRVR and MP2143GJ-Z, the FAN53611UC123X uniquely combines 1 A capability, 6 MHz operation for minimal passive size, programmable PFM/PWM mode, and external clock synchronization - making it optimal for ultra-compact, noise-sensitive, high-current portable applications where the 1.233 V output matches specific SoC I/O requirements.

Availability

FAN53611UC123X is available at Aetrix Electronics and suitable for mobile data cards, tablet core rails, ultra-mobile PC I/O supplies, and DSC/DVC image sensor biasing requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for FAN53611UC123X 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 supplier specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and portable electronics.

The FAN53611UC123X belongs to onsemi's high-frequency synchronous buck regulator product line, engineered specifically for space-constrained portable devices demanding ultra-small footprints, high light-load efficiency, and robust transient performance without external compensation.

FAQ

What is the output voltage tolerance of the FAN53611UC123X over temperature and load?

The FAN53611UC123X delivers a nominal 1.233 V output with guaranteed accuracy of ±4.2% (1.185 V to 1.281 V) across full load (0–1 A) and operating temperature (–40°C to +85°C). In PWM mode only, tolerance tightens to ±3.4% (1.192–1.274 V). This is confirmed in the Electrical Characteristics table under VO parameter for 1.233 V option.

Does the FAN53611UC123X include active output discharge?

No, the FAN53611UC123X does not include active output discharge. Per the Ordering Information table, "No" is explicitly listed under Active Discharge for this part number. Unlike variants ending in "AUC", this version leaves FB floating during shutdown, preventing uncontrolled discharge - a design choice for applications requiring hold-up or controlled power-down sequencing.

How does the MODE pin function on the FAN53611UC123X?

The MODE pin on the FAN53611UC123X serves three roles: (1) logic high (>1.2 V) forces fixed-frequency PWM operation; (2) logic low (<0.4 V) enables automatic PFM/PWM mode switching; (3) a 1.3–1.7 MHz square wave input synchronizes switching to 4× that frequency (5.2–6.8 MHz). It features internal Schmitt triggering for noise immunity.

What are the minimum recommended external components for the FAN53611UC123X?

The FAN53611UC123X requires three external components: a 470 nH shielded inductor (e.g., Murata LQM21PNR47MC0), a 2.2 µF X5R 0402 input capacitor placed within 2 mm of VIN and GND, and a 4.7 µF X5R 0402 output capacitor. These values are validated in the Recommended Operating Conditions and Applications Information sections.

What thermal protection features does the FAN53611UC123X provide?

The FAN53611UC123X incorporates thermal shutdown (TSD) that disables switching when junction temperature reaches 150°C, with 15°C hysteresis for automatic recovery. Thermal performance is characterized by θ_JA = 125°C/W on a 4-layer JEDEC-standard board. No external thermal pad or heatsink is required for 1 A operation at +85°C ambient with proper PCB copper area.

FAN53611UC123X 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):: 1.233V

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)

FAN53611UC123X FAQ

1.How can I place an order for FAN53611UC123X through Aetrix?

Please submit a Request for Quotation (RFQ) for FAN53611UC123X 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 FAN53611UC123X reliable?

The price and inventory of FAN53611UC123X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN53611UC123X is usually 5 days.

3.What payment methods are accepted for FAN53611UC123X?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN53611UC123X transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FAN53611UC123X?

FAN53611UC123X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FAN53611UC123X 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 FAN53611UC123X?

For technical support, including FAN53611UC123X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN53611UC123X requirements.

6.How does Aetrix verify that FAN53611UC123X is sourced from the original manufacturer or authorized distributors?

All FAN53611UC123X 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 FAN53611UC123X meets industry standards.

7.What is the process for return or replacement of FAN53611UC123X?

All FAN53611UC123X units undergo pre-shipment inspection (PSI). If there is an issue with FAN53611UC123X, 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 FAN53611UC123X part is unused and in its original packaging.

Return procedure for FAN53611UC123X:

1.Submit a request within 90 days.

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

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