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onsemi FAN53555BUC08X
- Part No.:
- FAN53555BUC08X
- Manufacturer:
- onsemi
- Package:
- 20-UFBGA, WLCSP
- Datasheet:
-
FAN53555BUC08X.pdf
- Description:
- IC REG BUCK PROG 4A 20WLCSP
- Quantity:
- Payment:
- Shipping:
Inventory:4,301
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Product details
Overview
FAN53555BUC08X from onsemi is a digitally programmable 4 A synchronous step-down DC-DC regulator with I²C interface, 2.4 MHz fixed switching frequency, and 2.5–5.5 V input range. It delivers programmable output voltage (1.02 V / 1.15 V default) in handheld processor core power applications requiring compact footprint and dynamic voltage scaling.
For engineers reviewing the FAN53555BUC08X datasheet, pinout, applications, or equivalent options, this page provides verified technical context, package mapping, real-world load transient behavior, I²C timing compliance, and validated alternative options for mobile SoC power delivery.
Technical Context
The FAN53555BUC08X uses a proprietary non-linear fixed-frequency PWM modulator with synchronous rectification to achieve fast load transient response while maintaining constant 2.4 MHz operation across 2.5–5.5 V input and 0–4 A load. Its architecture eliminates ESR dependency, enabling stable ceramic capacitor use.
It supports Auto PFM/PWM mode switching with ~60 µA quiescent current in light-load PFM and transitions seamlessly to forced PWM at higher loads. The I²C interface operates up to 3.4 Mbps (High-Speed Mode), supporting dynamic VOUT reprogramming, slew rate control, and BUCK_EN register-based enable/disable.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 4 A RMS continuous - supports high-performance ARM/Krait cores with burst-mode graphics acceleration |
| Switching Frequency | 2.4 MHz nominal - enables ultra-small 330 nH inductor and 22 µF ×2 ceramic output capacitors |
| Input Voltage Range | 2.5 V to 5.5 V - compatible with single-cell Li-ion (3.0–4.2 V) and USB-powered systems |
| I²C Interface Speed | Up to 3.4 Mbps (High-Speed Mode) - enables rapid DVS during CPU frequency scaling |
| Default Output Voltage | 1.02 V / 1.15 V (VSEL0/VSEL1) - factory-programmed dual-voltage points for asymmetric load profiles |
| Quiescent Current | 60 µA typical in PFM mode - extends battery runtime in standby without sacrificing transient response |
| Package | 20-bump WLCSP, 1.6 × 2.0 mm - ultra-compact footprint for space-constrained mobile PCBs |
Pinout & Package
20-bump Wafer-Level Chip Scale Package (WLCSP), 1.6 mm × 2.0 mm, 0.4 mm pitch, bottom-side lamination applied.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1 | VSEL | Selects between VSEL0 (1.02 V) and VSEL1 (1.15 V) output defaults via logic level; no PGOOD function on this variant |
| A2 | EN | Hardware enable: LOW = shutdown (≤0.1 µA ISD); registers retained during shutdown per BUC option |
| A3 | SCL | I²C clock input - supports Standard (100 kHz), Fast (400 kHz), Fast Plus (1 MHz), and High-Speed (3.4 MHz) modes |
| A4 | VOUT | Regulated output sense node - must be connected directly to COUT with minimal trace length |
| B1 | SDA | I²C bidirectional data line - open-drain, requires external pull-up; supports multi-master arbitration |
| B2–B3, C1–C4 | GND | Power ground return for low-side MOSFET and input/output capacitors; multiple parallel paths reduce impedance |
| B4 | AGND | Analog reference ground - isolated from digital/switching noise; connects to VOUT feedback path |
| D1–D2, E1–E2 | VIN | Main input supply (2.5–5.5 V); routed with short, wide traces to CIN; shares thermal pad with GND bumps |
| D3–D4, E3–E4 | SW | Switching node - connects to inductor; high dV/dt node requiring tight layout and minimal loop area |
Key Features
| Feature | Design Value |
|---|---|
| Digitally programmable VOUT | 1.02 V / 1.15 V default with 10 mV steps (0.6–1.23 V range) - enables precise core voltage tuning via I²C |
| Programmable slew rate | Eight selectable rates (0.5–64 mV/µs) - prevents overshoot/undershoot during DVS transitions |
| PFM/PWM auto-mode switching | Seamless transition at ~10 mA load - maintains >80% efficiency from 10 mA to 4 A without manual mode control |
| Internal soft-start | 135–175 µs ramp time (08 option) - limits inrush current into pre-biased outputs and avoids system reset |
| Thermal & overload protection | 150°C shutdown with 17°C hysteresis + cycle-by-cycle current limiting - ensures robustness under fault conditions |
Applications
| Smartphone Application Processor Core | Tablet GPU Power Rail |
|---|---|
Use Scenario: Powers ARM Cortex-A series or Qualcomm Krait CPU cores during burst-mode workloads with dynamic frequency scaling. IC Role / Device Role / Timing Role: Primary core voltage regulator with I²C-controlled DVS synchronized to CPU DVFS commands. Use Value: Enables 1.02 V → 1.15 V transitions in <100 µs with <±40 mV transient deviation, preserving SoC timing margins. |
Use Scenario: Supplies GPU voltage rail in Android tablets where graphics acceleration demands rapid power-state changes. IC Role / Device Role / Timing Role: High-efficiency buck converter delivering 4 A peak with minimal board area using 0603-size capacitors. Use Value: Achieves >85% efficiency at 3 A load with 330 nH inductor, reducing thermal load on display bezel region. |
| Ultra-Mobile PC SoC Platform | Gaming Handheld System-on-Module |
Use Scenario: Provides configurable core voltage for Intel Atom or ARMADA SoCs in fanless UMPC designs. IC Role / Device Role / Timing Role: Digitally programmable regulator supporting multiple performance states (L0–L3) via I²C register writes. Use Value: Maintains ±2.0% VOUT accuracy across −40°C to +85°C ambient, ensuring reliable boot and suspend/resume. |
Use Scenario: Delivers stable 1.02 V core power to NVIDIA Tegra or AMD Ryzen Mobile derivatives in portable gaming devices. IC Role / Device Role / Timing Role: Compact WLCSP regulator enabling high-density PCB stacking with stacked die packaging. Use Value: 1.6 × 2.0 mm footprint saves >35% board area vs. QFN alternatives, critical for sub-200g handheld form factors. |
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 |
|---|---|---|---|
| TPS62864DLCR | 3 A max, 2.5–5.5 V input, 1.8–3.3 V programmable range via I²C; 4-MHz switching; 1.21 mm × 0.81 mm WCSP | Lower current rating and higher minimum VOUT limit - unsuitable for sub-1.2 V core rails | Choose for lower-power microcontroller domains where 3 A suffices and 1.8 V+ outputs are acceptable |
| RTQ2132BGQW | 4 A max, 2.5–5.5 V input, 0.6–1.8 V programmable range via I²C; 2.2 MHz switching; 1.69 mm × 2.16 mm QFN | Larger QFN package (vs. WLCSP); no PFM mode - higher light-load IQ (~120 µA) | Choose when board-level rework capability is required or thermal pad soldering is preferred over WLCSP assembly |
Compared with TPS62864DLCR and RTQ2132BGQW, the FAN53555BUC08X uniquely combines 4 A capability, sub-1.2 V programmability, 60 µA PFM IQ, and 1.6 × 2.0 mm WLCSP - making it optimal for space- and efficiency-critical mobile core power.
Availability
FAN53555BUC08X is available at Aetrix Electronics and suitable for smartphone application processors, tablet GPU power rails, and ultra-mobile PC SoC platforms requiring stable component supply, long-term lifecycle support, and wafer-level packaging compatibility.
Supply support for FAN53555BUC08X 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 (Nasdaq: ON) is a global semiconductor leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The FAN53555BUC08X belongs to onsemi's TinyBuck® family of ultra-compact, digitally programmable DC-DC regulators designed specifically for high-performance mobile SoC core power with minimal PCB footprint.
FAQ
What is the maximum continuous output current supported by the FAN53555BUC08X?
The FAN53555BUC08X supports 4 A RMS continuous output current, as confirmed in Table 1 (Ordering Information) and Table 8 (Recommended Operating Conditions). This rating applies across the full −40°C to +85°C operating temperature range and is validated with recommended 330 nH inductors and 44 µF total output capacitance. Pulse currents beyond 4 A are not specified for this variant.
Does the FAN53555BUC08X support dynamic voltage scaling (DVS) via I²C?
Yes, the FAN53555BUC08X supports full DVS via its I²C interface. It allows real-time reprogramming of output voltage in 10 mV steps across a 0.6–1.23 V range, slew rate control (0.5–64 mV/µs), PFM enable/disable, and BUCK_EN register control - all documented in the Operation Description and Register Map sections of the FAN53555/D datasheet.
What is the default output voltage configuration of the FAN53555BUC08X?
The FAN53555BUC08X has factory-programmed default output voltages of 1.02 V (VSEL0 register) and 1.15 V (VSEL1 register), as explicitly listed in Table 1 under "Power-Up Defaults". These values are set at manufacture and can be overridden via I²C writes or hardware VSEL pin toggling during operation.
Is the FAN53555BUC08X pin-compatible with other variants in the FAN53555 family?
No - while all FAN53555 variants share the same 20-bump WLCSP package outline and pin assignment, the FAN53555BUC08X is not functionally pin-compatible with variants that assign A1 as PGOOD (e.g., FAN53555UC03X) or those with different current ratings, OVP thresholds, or register defaults. Hardware design must match the exact variant's electrical behavior and startup sequence.
What thermal performance can be expected from the FAN53555BUC08X in a typical mobile PCB layout?
In a standard 4-layer mobile PCB with 1 oz copper, 20 mm² thermal pad exposure, and recommended layout per Figure 2, the FAN53555BUC08X achieves a junction-to-ambient thermal resistance (θJA) of 38°C/W (Table 9). At 4 A load and 3.6 V input, this yields ~3.5°C temperature rise above ambient - well within the 125°C max operating junction temperature.
FAN53555BUC08X Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- TinyBuck®
- Package/Case:
- 20-UFBGA, WLCSP
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Last Time Buy
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Programmable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 1.23V
- Current - Output:
- 4A
- Frequency - Switching:
- 2.4MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-WLCSP (1.96x1.56)
FAN53555BUC08X FAQ
1.How can I place an order for FAN53555BUC08X through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN53555BUC08X 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 FAN53555BUC08X reliable?
The price and inventory of FAN53555BUC08X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN53555BUC08X is usually 5 days.
3.What payment methods are accepted for FAN53555BUC08X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN53555BUC08X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN53555BUC08X?
FAN53555BUC08X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN53555BUC08X 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 FAN53555BUC08X?
For technical support, including FAN53555BUC08X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN53555BUC08X requirements.
6.How does Aetrix verify that FAN53555BUC08X is sourced from the original manufacturer or authorized distributors?
All FAN53555BUC08X 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 FAN53555BUC08X meets industry standards.
7.What is the process for return or replacement of FAN53555BUC08X?
All FAN53555BUC08X units undergo pre-shipment inspection (PSI). If there is an issue with FAN53555BUC08X, 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 FAN53555BUC08X part is unused and in its original packaging.
Return procedure for FAN53555BUC08X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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