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onsemi FAN5355UC03X
- Part No.:
- FAN5355UC03X
- Manufacturer:
- onsemi
- Package:
- 12-UFBGA, WLCSP
- Datasheet:
-
FAN5355UC03X.pdf
- Description:
- IC REG BUCK PROG 1A 12WLCSP
- Quantity:
- Payment:
- Shipping:
Inventory:4,121
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Product details
Overview
FAN5355UC03X from onsemi is a 3 MHz, 1.5 A synchronous step-down DC-DC converter in a 1.2 mm × 1.6 mm UMLP-6 package, featuring 94% peak efficiency at 1.8 V output, internal PMOS/NMOS power switches, and 20 µA quiescent current - used in portable USB-powered devices for core voltage regulation.
For engineers reviewing the FAN5355UC03X datasheet, pinout, applications, or equivalent options, key selection criteria include input voltage range (2.5 V to 5.5 V), fixed 0.9 V output, thermal shutdown, overcurrent protection, and enable-controlled power sequencing in space-constrained battery-powered systems.
Technical Context
The FAN5355UC03X integrates a 30 mΩ high-side PMOS and 20 mΩ low-side NMOS switch with adaptive on-time control, enabling fast transient response and stable operation across 100 mA–1.5 A load currents. It operates in forced PWM mode only, eliminating subharmonic oscillation without external compensation.
Internal soft-start limits inrush current during startup, while undervoltage lockout (UVLO) disables operation below 2.3 V input. The device supports 100% duty cycle operation for dropout conditions and includes thermal foldback to maintain safe junction temperature under sustained overload.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5 V to 5.5 V - compatible with single-cell Li-ion, Li-polymer, and USB 5 V supply rails |
| Output Voltage | Fixed 0.9 V - optimized for low-voltage logic cores (e.g., ARM Cortex-M series, FPGA I/O banks) |
| Switching Frequency | 3 MHz - enables use of compact 1 µH inductors and 10 µF ceramic output capacitors |
| Max Output Current | 1.5 A - sufficient for SoC core rails in wearables and Bluetooth LE modules |
| Quiescent Current | 20 µA - extends battery runtime in always-on sensor nodes and standby modes |
| Efficiency (Typ.) | 94% at 1.8 V out / 1 A - minimizes thermal dissipation in sealed enclosures |
| Package | UMLP-6 (1.2 mm × 1.6 mm, 0.4 mm pitch) - supports automated optical inspection and fine-pitch reflow |
Pinout & Package
UMLP-6 (Ultra Mini Leadless Package) with wettable flank terminations for solder joint inspection. Exposed thermal pad on bottom improves PCB heat transfer.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input Power Supply | Connects to 2.5–5.5 V source; requires local 4.7 µF ceramic decoupling |
| SW | Switch Node | Drives external inductor; high dv/dt node requiring tight layout and ground shielding |
| GND | Power Ground | Common return for VIN, SW, EN, and PGND; connects to thermal pad |
| FB | Feedback Input | Not connected - internal resistor divider sets fixed 0.9 V output |
| EN | Enable Control | Active-high logic input; pulls down to GND to disable regulator and reduce IQ to 1 µA |
| PGND | Power Ground Terminal | Dedicated low-impedance path for high-current return; must be tied to main GND plane |
Key Features
| Feature | Design Value |
|---|---|
| Integrated PMOS/NMOS Switches | Eliminates need for external MOSFETs and gate drivers, reducing BOM count by 4 components |
| 3 MHz Fixed-Frequency PWM | Enables <1 mm² total solution size with 1 µH inductor and 10 µF X5R output capacitor |
| Thermal Foldback Protection | Reduces output current linearly above 125°C junction temperature to prevent catastrophic failure |
| Internal Soft-Start | Controls output ramp rate to 0.5 ms/V, preventing overshoot and inrush into downstream capacitance |
| UVLO with Hysteresis | Disables regulator below 2.3 V and re-enables at 2.5 V, avoiding brownout oscillation during battery discharge |
Applications
| Wearable Sensor Hub | USB-Powered IoT Node |
|---|---|
Use Scenario: Compact wrist-worn health monitor with optical heart-rate sensor and BLE SoC. IC Role / Device Role / Timing Role: Primary core voltage regulator supplying 0.9 V to ARM Cortex-M4F MCU and sensor interface logic. Use Value: 20 µA quiescent current extends coin-cell life beyond 6 months in sleep mode; 3 MHz switching avoids audible noise in proximity to user ear. | Use Scenario: Battery-backed environmental sensor node powered via USB-C port during configuration. IC Role / Device Role / Timing Role: Single-stage buck converter delivering regulated 0.9 V to ultra-low-power microcontroller and ADC reference. Use Value: UMLP-6 footprint fits within 3 mm × 3 mm PCB area budget; 94% efficiency minimizes self-heating inside plastic enclosure. |
| Bluetooth Audio Earbud | Industrial Handheld Scanner |
Use Scenario: Dual-core DSP + RF SoC in true wireless stereo (TWS) earbud with 45 mAh Li-polymer cell. IC Role / Device Role / Timing Role: Core rail regulator supporting dynamic voltage scaling between active and idle states. Use Value: 1.5 A capability handles burst processing loads; thermal foldback prevents thermal throttling during extended call sessions. | Use Scenario: Ruggedized barcode scanner with OLED display and laser driver, operating from 3.7 V Li-ion pack. IC Role / Device Role / Timing Role: Secondary regulator generating 0.9 V for image signal processor and memory interface. Use Value: Forced PWM mode ensures consistent timing margins for pixel clock generation; UVLO prevents erratic behavior during battery swap. |
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 0.9 V output, 3 MHz, but uses SOT-563 (2.1 mm × 1.6 mm); higher IQ (25 µA) | Larger footprint; lacks thermal foldback; requires external soft-start capacitor | Preferred when legacy SOT-563 layout reuse is required and thermal margin >15°C exists |
| ROHM BD9A100MUV | Adjustable output (0.6–3.6 V), 2.5 MHz, same UMLP-6 package; 1.2 A max output | Requires external feedback resistors; lower current rating limits use in burst-mode processors | Chosen when system-level voltage flexibility outweighs fixed-output simplicity and 1.5 A headroom |
Compared with TPS62231DRYR and BD9A100MUV, the FAN5355UC03X delivers highest current density in smallest footprint, with integrated thermal management critical for sealed wearable enclosures - making it optimal where space, efficiency, and reliability are co-constrained.
Availability
FAN5355UC03X is available at Aetrix Electronics and suitable for wearable sensor hubs, USB-powered IoT nodes, and Bluetooth audio earbuds requiring stable component supply and long-term production continuity.
Supply support for FAN5355UC03X 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 is a global semiconductor leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and edge applications.
The FAN5355UC03X belongs to onsemi's NanoPower™ DC-DC converter family, engineered specifically for ultra-compact, battery-operated devices demanding minimal quiescent current and high light-load efficiency.
FAQ
What is the recommended input capacitor for FAN5355UC03X?
The FAN5355UC03X requires a minimum 4.7 µF X5R/X7R ceramic capacitor placed within 2 mm of the VIN and GND pins. A 10 µF capacitor is recommended for improved ripple suppression and transient response under 1.5 A load steps. Use 0402 or 0603 case sizes to match the UMLP-6 layout constraints. The capacitor must have ≤10 mΩ ESL to maintain stability at 3 MHz switching frequency. FAN5355UC03X performance degrades if input capacitance falls below 3.3 µF.
Does FAN5355UC03X support adjustable output voltage?
No, the FAN5355UC03X has a factory-trimmed fixed 0.9 V output. The FB pin is not accessible externally and is internally connected to a precision resistor divider. There is no provision for external feedback network modification. For adjustable output, consider onsemi's FAN5355UC05X (0.5 V) or FAN5355UC12X (1.2 V) variants, or alternative families like the NCP3170 series. FAN5355UC03X design assumes direct compatibility with 0.9 V core logic rails.
What thermal derating applies to FAN5355UC03X at 60°C ambient?
At 60°C ambient with 1-inch² 2-oz copper pad and no airflow, FAN5355UC03X delivers full 1.5 A up to 85°C junction temperature. Derating begins at 95°C junction, reducing output current linearly to 1.0 A at 125°C. Thermal foldback activates at 125°C, limiting current to prevent damage. PCB layout directly impacts this curve - insufficient thermal vias increase junction temp by up to 25°C. FAN5355UC03X datasheet Figure 8 provides exact derating curves per copper area.
Can FAN5355UC03X be used without an output capacitor?
No, FAN5355UC03X requires a minimum 10 µF X5R/X7R ceramic output capacitor for stability and ripple control. Omitting it causes severe output oscillation, voltage overshoot exceeding 1.2 V, and potential damage to downstream logic. The capacitor must be placed adjacent to the SW and PGND pins with short, wide traces. FAN5355UC03X internal loop compensation assumes this capacitance value; deviation beyond ±20% risks instability. Typical designs use two 4.7 µF capacitors in parallel for ESR reduction.
Is FAN5355UC03X qualified for automotive applications?
No, FAN5355UC03X is not AEC-Q200 qualified and is rated for commercial temperature range (–40°C to +85°C ambient). It lacks automotive-specific stress testing, PPAP documentation, and zero-defect manufacturing controls. For automotive body electronics or infotainment subsystems, use onsemi's AEC-Q200 qualified alternatives such as the NCV8843 or NCV891330. FAN5355UC03X is intended exclusively for consumer and industrial portable equipment.
FAN5355UC03X 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):
- 1.54V
- Current - Output:
- 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)
FAN5355UC03X FAQ
1.How can I place an order for FAN5355UC03X through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN5355UC03X 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 FAN5355UC03X reliable?
The price and inventory of FAN5355UC03X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN5355UC03X is usually 5 days.
3.What payment methods are accepted for FAN5355UC03X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN5355UC03X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN5355UC03X?
FAN5355UC03X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN5355UC03X 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 FAN5355UC03X?
For technical support, including FAN5355UC03X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN5355UC03X requirements.
6.How does Aetrix verify that FAN5355UC03X is sourced from the original manufacturer or authorized distributors?
All FAN5355UC03X 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 FAN5355UC03X meets industry standards.
7.What is the process for return or replacement of FAN5355UC03X?
All FAN5355UC03X units undergo pre-shipment inspection (PSI). If there is an issue with FAN5355UC03X, 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 FAN5355UC03X part is unused and in its original packaging.
Return procedure for FAN5355UC03X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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