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onsemi FAN5355UC08X
- Part No.:
- FAN5355UC08X
- Manufacturer:
- onsemi
- Package:
- 12-UFBGA, WLCSP
- Datasheet:
-
FAN5355UC08X.pdf
- Description:
- IC REG BUCK PROG 1.1A 12WLCSP
- Quantity:
- Payment:
- Shipping:
Inventory:3,054
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Product details
Overview
FAN5355UC08X from ON Semiconductor (formerly Fairchild) is a digitally programmable synchronous step-down DC-DC regulator optimized for mobile processor core and memory power delivery. It delivers up to 1.1 A output current, operates at a fixed 3 MHz switching frequency, supports I²C interface up to 3.4 Mbps, and provides 6-bit programmable VOUT from 0.75 V to 1.4375 V with ±2% DC accuracy - enabling dynamic voltage scaling in smartphone application processors.
For engineers reviewing the FAN5355UC08X datasheet, pinout, applications, or equivalent options, key selection considerations include its WLCSP-12 package footprint, 1.1 A current rating with thermal shutdown at 150°C, PFM/PWM seamless mode transition, and support for external clock synchronization - all critical for space-constrained, battery-powered portable designs requiring high light-load efficiency and fast transient response.
Technical Context
The FAN5355UC08X implements a non-linear control architecture for ultra-fast load transient response and stable regulation with minimal external components. Its integrated dual-MOSFET power stage features 145 mΩ P-channel and 75 mΩ N-channel RDS(ON) in WLCSP package, enabling high-efficiency operation across 2.7–5.5 V input range.
It combines hardware-based VSEL pin programming with full I²C register access for dynamic reconfiguration of output voltage (12.5 mV steps), operating mode (PFM/forced PWM), soft-start slew rate, and SYNC enable - all while maintaining <7 μs VOUT settling time and <200 nA shutdown current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 1.1 A maximum continuous - supports high-performance mobile SoC core rails without derating at 85°C ambient. |
| Input Voltage Range | 2.7 V to 5.5 V - compatible with single-cell Li-ion batteries and intermediate supply rails. |
| Switching Frequency | 3.0 MHz nominal (2.65–3.35 MHz) - enables use of 1 μH inductor and compact 0603 capacitors. |
| VOUT Programming | 0.75 V to 1.4375 V in 12.5 mV steps via I²C or pin-selectable VSEL - meets SmartReflex™-compliant DVFS requirements. |
| Efficiency | 93% peak at 3 MHz - achieved with synchronous rectification and low-RDS(ON) MOSFETs in WLCSP package. |
| Quiescent Current | 37 μA in PFM mode - extends battery life during idle/sleep states in always-on mobile subsystems. |
| Protection Features | Short-circuit protection, thermal shutdown (150°C), over-current limit (1.4–1.65 A), and UVLO with 250 mV hysteresis - ensures robust operation under fault conditions. |
Pinout & Package
Package: Wafer-Level Chip-Scale Package (WLCSP-12), 2.23 mm × 1.46 mm, 0.4 mm pitch, bottom-side solder bumps.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1, B1 | PGND | Power ground return for internal MOSFETs - must connect directly to CIN ground plane with shortest possible trace. |
| A2 | SW | Switching node - connects to inductor; high dv/dt node requiring tight layout and guard ring. |
| A3 | PVIN | Main power input - ties to battery or source rail; requires local 4.7 μF ceramic capacitor. |
| B2 | SYNC | External clock synchronization input - enables multi-rail phase alignment or noise frequency steering. |
| B3 | AVIN | Analog power supply - powers internal reference and control circuitry; decoupled separately from PVIN. |
| C1 | AGND | Analog ground reference - isolated signal ground for feedback and I²C; connected to system AGND only at single point. |
| C2 | EN | Enable control - active-high logic input; pulls device into <200 nA shutdown when low. |
| C3 | SDA | I²C serial data line - supports Fast/High-Speed modes up to 3.4 Mbps for dynamic voltage updates. |
| D1 | VOUT | Output voltage monitor - high-impedance feedback input; tied directly to regulated output node. |
| D2 | VSEL | Voltage select control - selects between two pre-programmed VOUT defaults (1.05 V / 1.20 V) before I²C initialization. |
| D3 | SCL | I²C serial clock line - synchronized with SDA for register read/write and mode configuration. |
Key Features
| Feature | Design Value |
|---|---|
| 3 MHz fixed-frequency PWM + PFM mode | Enables 1 μH inductor solution and reduces EMI filtering burden while maintaining >93% efficiency at light loads. |
| 6-bit I²C-programmable VOUT (0.75–1.4375 V) | Supports fine-grained dynamic voltage scaling for ARM Cortex-A series and OMAP processors with 12.5 mV resolution. |
| Smooth PWM-to-PFM transition | Eliminates output voltage glitches during mode switching - critical for noise-sensitive RF and audio subsystems. |
| On-the-fly external clock synchronization | Allows precise timing coordination across multiple FAN5355UC08X regulators in multi-rail PMIC architectures. |
| 18.75 V/ms soft-start slew rate | Controls inrush current during power-up and prevents input voltage droop on shared battery rails. |
| Thermal shutdown with 20°C hysteresis | Prevents cumulative thermal stress in dense mobile PCB layouts; auto-recovery avoids system lockup. |
Applications
| Smartphone Application Processor Core | LPDDR2 Memory Power Rail |
|---|---|
|
Use Scenario: Powers ARM-based application processor cores (e.g., Qualcomm Snapdragon, TI OMAP) requiring dynamically scaled voltage between 0.75 V and 1.4375 V during performance state transitions. IC Role / Device Role / Timing Role: Primary core voltage regulator with I²C-controlled DVFS, delivering up to 1.1 A with <7 μs VOUT settling time during frequency scaling events. Use Value: Enables energy-efficient operation by matching supply voltage precisely to CPU workload - reducing dynamic power by up to 50% versus fixed-voltage solutions. |
Use Scenario: Supplies regulated 1.2 V or 1.35 V to LPDDR2 SDRAM modules in smartphones and tablets, where tight voltage tolerance and fast transient response are mandatory. IC Role / Device Role / Timing Role: Dedicated memory rail regulator with ±2% DC accuracy and <2.2 mVPP ripple in PWM mode - meeting JEDEC LPDDR2 VDDQ spec. Use Value: Prevents memory read/write errors during burst data transfers by maintaining voltage within ±3% under 50–400 mA load steps. |
| Wi-Fi/Baseband Modem Power | Ultra-Mobile PC SoC I/O Domain |
|
Use Scenario: Powers 3G/LTE/Wi-Fi baseband modems (e.g., Broadcom BCM43xx, Qualcomm QCA9xxx) requiring clean, low-noise 1.05–1.20 V supplies during RF transmission bursts. IC Role / Device Role / Timing Role: Low-EMI, high-PSRR buck regulator with 3 MHz switching and external SYNC capability - minimizing interference with adjacent RF receivers. Use Value: Achieves >40 dB PSRR at 100 kHz and <20 mVPP ripple in PFM mode - preserving RF sensitivity and reducing bit error rates. |
Use Scenario: Delivers 1.8 V I/O supply to Intel Atom or AMD Jaguar SoCs in ultra-mobile PCs, where board area and thermal density constrain traditional PMIC solutions. IC Role / Device Role / Timing Role: Compact WLCSP-12 regulator supporting 1.1 A peak current with 2.23 × 1.46 mm footprint - enabling direct placement beneath SoC BGA. Use Value: Reduces total solution size by 40% versus MLP-10 alternatives while maintaining thermal performance via copper pillar bump interconnects. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digitally programmable buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62260DRVR | 1.2 A, 2.25 MHz, I²C interface, 1.6–6.5 V input, 0.6–5.5 V output - higher input range but no VSEL pin; uses different register map. | Targets broader industrial input ranges; lacks hardware VSEL fallback - requires full I²C initialization before regulation. | Choose TPS62260DRVR if system design mandates wider VIN or needs higher output voltage flexibility beyond 1.4375 V. |
| RTQ2132BWGE | 1.2 A, 3 MHz, I²C interface, 2.5–5.5 V input, 0.6–3.3 V output - includes built-in soft-start timer and adjustable current limit, but larger 12-pin WDFN package (2.5 × 2.5 mm). | Offers configurable over-current threshold and longer soft-start options; less suitable for ultra-thin mobile form factors due to 0.55 mm height. | Choose RTQ2132BWGE if design requires field-adjustable current limiting or extended soft-start duration for high-capacitance loads. |
Compared with TPS62260DRVR and RTQ2132BWGE, the FAN5355UC08X uniquely combines 1.1 A capability in a 2.23 × 1.46 mm WLCSP, pin-selectable startup voltage, and guaranteed 3 MHz operation - making it optimal for space-constrained mobile SoC core rails where footprint and fast DVFS response are prioritized over wide-VIN flexibility or programmable OCP.
Availability
FAN5355UC08X is available at Aetrix Electronics and suitable for smartphone application processor core supplies, LPDDR2 memory rails, Wi-Fi/baseband modem power, and ultra-mobile PC SoC I/O domains requiring stable component supply, consistent WLCSP-12 sourcing, and long-term lifecycle support.
Supply support for FAN5355UC08X 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 (formerly Fairchild Semiconductor) is a global leader in intelligent power and sensing technologies, serving automotive, industrial, cloud computing, and mobile markets with energy-efficient semiconductor solutions.
The FAN5355UC08X belongs to ON Semiconductor's high-frequency mobile PMIC portfolio, designed specifically for dynamic voltage scaling in battery-powered handheld devices - emphasizing ultra-small footprint, high light-load efficiency, and seamless integration with application processor DVFS controllers.
FAQ
What is the maximum output current capability of the FAN5355UC08X?
The FAN5355UC08X delivers up to 1.1 A continuous output current under recommended operating conditions (TA ≤ 85°C, 2.7–5.5 V input). Its over-current limit is specified at 1.4–1.65 A depending on input voltage, and thermal shutdown activates at 150°C junction temperature to protect the device during sustained overload. The FAN5355UC08X maintains regulation up to its rated current in both PWM and PFM modes.
Does the FAN5355UC08X support external clock synchronization?
Yes, the FAN5355UC08X supports external clock synchronization via the SYNC pin. When the SYNC_EN bit is set high, the regulator locks to an external clock signal within 2.7–3.3 MHz range and 20–80% duty cycle. This feature allows precise timing alignment across multiple FAN5355UC08X devices in multi-rail systems, reducing beat-frequency noise and simplifying EMI filter design.
What is the VOUT programming resolution and range for the FAN5355UC08X?
The FAN5355UC08X offers 6-bit digital VOUT programming via I²C, providing 64 discrete steps from 0.75 V to 1.4375 V in 12.5 mV increments. This range is confirmed for Option 08 in the ordering table and datasheet Electrical Specifications. The VSEL pin provides hardware-selectable default voltages of 1.05 V or 1.20 V at power-up before I²C configuration.
How does the FAN5355UC08X handle light-load efficiency?
The FAN5355UC08X automatically transitions from fixed-frequency PWM to variable-frequency PFM mode under light loads, achieving 37 μA quiescent current and maintaining >85% efficiency down to 1 mA output. The transition is glitch-free, with no output voltage disturbance, and PFM mode remains active during soft-start to prevent reverse current flow into partially charged output capacitors.
What package type and dimensions does the FAN5355UC08X use?
The FAN5355UC08X is packaged in a Wafer-Level Chip-Scale Package (WLCSP-12) measuring 2.23 mm × 1.46 mm with 0.4 mm pitch and 12 solder bumps on the bottom. This ultra-compact footprint enables direct placement beneath mobile SoCs and eliminates PCB routing congestion associated with larger MLP or QFN packages.
FAN5355UC08X Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 12-UFBGA, WLCSP
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Programmable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.75V
- Voltage - Output (Max):
- 1.44V
- Current - Output:
- 1.1A
- Frequency - Switching:
- 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-WLCSP (2.23x1.46)
FAN5355UC08X FAQ
1.How can I place an order for FAN5355UC08X through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN5355UC08X 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 FAN5355UC08X reliable?
The price and inventory of FAN5355UC08X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN5355UC08X is usually 5 days.
3.What payment methods are accepted for FAN5355UC08X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN5355UC08X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN5355UC08X?
FAN5355UC08X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN5355UC08X 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 FAN5355UC08X?
For technical support, including FAN5355UC08X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN5355UC08X requirements.
6.How does Aetrix verify that FAN5355UC08X is sourced from the original manufacturer or authorized distributors?
All FAN5355UC08X 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 FAN5355UC08X meets industry standards.
7.What is the process for return or replacement of FAN5355UC08X?
All FAN5355UC08X units undergo pre-shipment inspection (PSI). If there is an issue with FAN5355UC08X, 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 FAN5355UC08X part is unused and in its original packaging.
Return procedure for FAN5355UC08X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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