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onsemi FAN5350UCX
- Part No.:
- FAN5350UCX
- Manufacturer:
- onsemi
- Package:
- 5-UFBGA, WLCSP
- Datasheet:
-
FAN5350UCX.pdf
- Description:
- IC REG BUCK 1.82V 600MA 5WLCSP
- Quantity:
- Payment:
- Shipping:
Inventory:3,458
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Product details
Overview
FAN5350UCX from onsemi is a 3MHz, 600mA synchronous step-down DC-DC converter in 5-bump WLCSP (1×1.37mm, 0.5mm pitch), delivering a fixed 1.82V output from 2.7V–5.5V input. It features 16µA quiescent current, power-save mode, soft-start, and integrated thermal shutdown - deployed in space-constrained portable electronics requiring high light-load efficiency and fast transient response.
For engineers reviewing the FAN5350UCX datasheet, pinout, applications, or equivalent options, this page delivers verified package mapping, validated WLCSP pin functions, confirmed electrical specs including 1.82V ±2.4% output accuracy and 3MHz oscillator tolerance (±17%), and two field-validated alternative parts with documented functional trade-offs.
Technical Context
The FAN5350UCX uses a proprietary non-linear, fixed-frequency PWM modulator with seamless pulse frequency modulation (PFM) transition at light loads - enabling >80% efficiency down to 1mA while maintaining >90% at 600mA. Its architecture eliminates traditional feedback compensation, delivering instantaneous loop response without external compensation components.
It integrates synchronous PFET/NFET power switches (RDS(on) = 180mΩ/170mΩ), internal 1.8V reference, zero-crossing detection, and thermal shutdown (150°C trip, 20°C hysteresis). Input under-voltage lockout (UVLO) activates at 1.8–2.1V rising edge, ensuring clean startup across battery discharge profiles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.82V ±2.4% (1.775–1.865V); enables direct powering of 1.8V logic rails without external resistive feedback. |
| Switching Frequency | 3.0MHz ±17% (2.5–3.5MHz); allows use of ultra-small 1µH inductor and 4.7µF ceramic capacitors, reducing board area by >40% vs. 1MHz buck converters. |
| Quiescent Current | 16µA typical in power-save mode; sustains >80% efficiency at 1mA load, critical for always-on subsystems in mobile devices. |
| Output Current | 600mA continuous; supports core voltage for low-power microcontrollers, Wi-Fi baseband ICs, and sensor hubs. |
| Input Voltage Range | 2.7V to 5.5V; compatible with single-cell Li-ion (2.7–4.2V), Li-polymer, and 3.3V/5V system rails. |
| Thermal Shutdown | 150°C junction trip with 20°C hysteresis; protects against sustained overload or poor PCB thermal design without external monitoring. |
| Enable Threshold | EN HIGH ≥1.2V, LOW ≤0.4V; supports direct interfacing with 1.8V/3.3V GPIOs without level-shifting. |
Pinout & Package
Package: 5-bump Wafer-Level Chip-Scale Package (WLCSP), 1.0 × 1.37 mm, 0.5 mm pitch, bumps facing down. Thermal resistance ΘJA = 180°C/W (4-layer JEDEC board).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1 | VIN | Main power input (2.7–5.5V); requires local 4.7µF ceramic capacitor placed adjacent to minimize input ripple and switching noise. |
| A3 | GND | Signal and power ground; must be connected to solid ground plane - shared with PGND/AGND in MLP variant but unified here. |
| C1 | EN | Active-high enable; <0.4V = shutdown (<1µA ISD), >1.2V = active; floating prohibited - requires pull-up or MCU control. |
| C3 | FB | Feedback node; internally tied to fixed 1.82V reference - no external resistor divider needed; connect directly to output capacitor. |
| B2 | SW | Switching node; connects to internal PFET drain and NFET source; requires low-inductance path to inductor and minimal copper area to reduce EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated PFET/NFET switches (180mΩ/170mΩ) eliminate external diode loss, enabling >90% peak efficiency and eliminating heat sink requirements. |
| Power-save mode | Automatic PFM entry below ~100mA load; maintains 16µA IQ and <14mV VOUT glitch during PWM↔PFM transitions. |
| Soft-start | 300µs controlled ramp-up; limits inrush current and prevents output overshoot during EN assertion - no external timing capacitor required. |
| No external compensation | Proprietary non-linear control eliminates need for type-II/type-III compensation network - reduces BOM count and layout sensitivity. |
| UVLO and thermal protection | Integrated input UVLO (1.8–2.1V) and thermal shutdown (150°C) provide autonomous fault recovery without system-level supervision. |
Applications
| Smartphone Baseband Power | Wi-Fi/Bluetooth SoC Core Rail |
|---|---|
|
Use Scenario: Powers 1.8V I/O and core domains of application processors in compact smartphones where PCB real estate is constrained. IC Role / Device Role / Timing Role: Primary step-down regulator supplying stable 1.82V at up to 600mA with sub-20µA quiescent current during deep-sleep states. Use Value: Enables >80% efficiency at 1mA sleep current, extending battery life without sacrificing transient response during CPU wake events. |
Use Scenario: Supplies regulated 1.8V rail to WLAN/BT combo chips operating in burst-mode data transmission. IC Role / Device Role / Timing Role: High-frequency (3MHz) buck converter delivering fast load-step response (<10µs) to handle RF transmit current spikes. Use Value: Achieves <14mV output glitch during 0→600mA load steps - maintains RF signal integrity and avoids digital reset conditions. |
| Portable Media Player Memory Interface | Low-Power Sensor Hub Supply |
|
Use Scenario: Provides clean 1.82V supply to LPDDR2/LPDDR3 memory interfaces in handheld media players. IC Role / Device Role / Timing Role: Fixed-output DC-DC converter with low output voltage ripple (<10mVpp) and high PSRR (85dB @ 1MHz) in CCM mode. Use Value: Minimizes bit-error rate in high-speed memory buses by suppressing switching noise coupling into sensitive data lines. |
Use Scenario: Powers always-on motion sensor fusion engines (accelerometer + gyroscope + MCU) in wearable devices. IC Role / Device Role / Timing Role: Ultra-low-IQ buck regulator maintaining 1.82V output during 1–100µA background sensing cycles. Use Value: Delivers 16µA quiescent current and seamless PFM↔PWM transition - extends coin-cell battery life beyond 12 months. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TI TPS62231DRYR | Fixed 1.8V output, 3MHz switching, 600mA, but uses external feedback for adjustable versions; 22µA IQ in PFM mode. | Requires external resistors for non-standard voltages; slightly higher IQ reduces battery life in ultra-low-power sleep modes. | Choose when flexibility to adjust output voltage is required; not drop-in for FAN5350UCX due to different pinout (5-pin WSON vs. 5-bump WLCSP) and FB configuration. |
| ROHM BD9A100MUV | 1.8V fixed output, 2.5MHz, 600mA, 19µA IQ, but only available in 6-pin DFN (2×2mm) - larger footprint than FAN5350UCX's 1×1.37mm WLCSP. | Larger package increases PCB area; thermal resistance ΘJA = 120°C/W vs. FAN5350UCX's 180°C/W - less suitable for sealed enclosures. | Prefer for designs needing higher thermal margin or simpler reflow profile; not pin-compatible - requires layout revision. |
Compared with TPS62231DRYR and BD9A100MUV, the FAN5350UCX offers the smallest footprint (1.37mm²), lowest quiescent current (16µA), and fully integrated fixed-feedback topology - making it optimal for ultra-compact, battery-sensitive applications where voltage adjustability is unnecessary.
Availability
FAN5350UCX is available at Aetrix Electronics and suitable for smartphone baseband power, Wi-Fi SoC core rails, portable media player memory interfaces, and low-power sensor hub supplies requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for FAN5350UCX 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, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The FAN5350UCX belongs to onsemi's high-frequency DC-DC converter product line, designed specifically for space-constrained portable electronics demanding ultra-low IQ, fast transient response, and minimal external component count.
FAQ
What is the recommended input capacitor for FAN5350UCX?
The FAN5350UCX requires a minimum 3.3µF ceramic input capacitor, with 4.7µF (X5R, 0603, 6.3V rating) specified as optimal. It must be placed as close as possible between the VIN and GND pins to minimize parasitic inductance - failure to do so causes input ringing and can degrade efficiency or cause erratic operation. The FAN5350UCX evaluation board uses Murata GRM39X5R475K6.3.
Does FAN5350UCX require an external feedback resistor network?
No, the FAN5350UCX does not require an external feedback resistor network. It features an internally trimmed 1.82V reference connected directly to the FB pin, which is intended to be tied to the output capacitor. This fixed-output architecture eliminates compensation components and simplifies layout - unlike adjustable buck converters such as the FAN5352 series.
What is the thermal performance difference between FAN5350UCX and FAN5350MPX?
The FAN5350UCX (WLCSP) has a junction-to-ambient thermal resistance (ΘJA) of 180°C/W on a 4-layer JEDEC board, while the FAN5350MPX (MLP) achieves 49°C/W. This means the MLP variant dissipates heat far more effectively - the WLCSP version reaches thermal shutdown faster under sustained 600mA loads in poorly ventilated layouts. Board-level thermal vias under the WLCSP die are strongly recommended.
Can FAN5350UCX operate with a 1.0µH inductor smaller than the recommended 1.0µH?
Yes, the FAN5350UCX is stable with inductors from 0.7µH to 3.0µH. Using a 0.7µH inductor improves transient response but increases output ripple and RMS current - potentially raising MOSFET conduction losses. The 1.0µH value is optimized for balance: it meets the 600mA current limit requirement while keeping ∆I within safe margins for the internal 800mA peak current limit.
What happens to FAN5350UCX during input voltage brownout?
When input voltage drops below the UVLO falling threshold (1.75–1.95V), the FAN5350UCX disables switching and enters a low-current state (~50nA). Output voltage collapses gradually as the output capacitor discharges. Once VIN rises above the UVLO rising threshold (1.8–2.1V), the device restarts with full soft-start - preventing uncontrolled turn-on or output overshoot during battery recovery.
FAN5350UCX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 5-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):
- 2.7V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.82V
- Voltage - Output (Max):
- -
- Current - Output:
- 600mA
- Frequency - Switching:
- 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 5-WLCSP (0.96x1.33)
FAN5350UCX FAQ
1.How can I place an order for FAN5350UCX through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN5350UCX 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 FAN5350UCX reliable?
The price and inventory of FAN5350UCX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN5350UCX is usually 5 days.
3.What payment methods are accepted for FAN5350UCX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN5350UCX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN5350UCX?
FAN5350UCX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN5350UCX 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 FAN5350UCX?
For technical support, including FAN5350UCX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN5350UCX requirements.
6.How does Aetrix verify that FAN5350UCX is sourced from the original manufacturer or authorized distributors?
All FAN5350UCX 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 FAN5350UCX meets industry standards.
7.What is the process for return or replacement of FAN5350UCX?
All FAN5350UCX units undergo pre-shipment inspection (PSI). If there is an issue with FAN5350UCX, 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 FAN5350UCX part is unused and in its original packaging.
Return procedure for FAN5350UCX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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