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onsemi FAN53555BUC18X
- Part No.:
- FAN53555BUC18X
- Manufacturer:
- onsemi
- Package:
- 20-UFBGA, WLCSP
- Datasheet:
-
FAN53555BUC18X.pdf
- Description:
- IC REG BUCK PROG 5A 20WLCSP
- Quantity:
- Payment:
- Shipping:
Inventory:2,275
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Product details
Overview
FAN53555BUC18X from onsemi is a digitally programmable 5 A synchronous step-down DC-DC regulator with I²C interface, fixed 2.4 MHz switching frequency, 2.5–5.5 V input range, and factory-programmed 1.02 V / 1.15 V dual-voltage default output. It delivers >80% efficiency from 10 mA to 5 A load and supports fast load transients in mobile processor core power applications.
For engineers reviewing the FAN53555BUC18X datasheet, pinout, applications, or equivalent options, key selection criteria include its WLCSP-20 package footprint, 10 mV programmable output steps (0.6–1.23 V), PFM/PWM mode auto-selection, 60 µA quiescent current, and integrated soft-start with VOUT discharge control.
Technical Context
The FAN53555BUC18X uses a proprietary non-linear fixed-frequency PWM modulator with synchronous rectification, enabling stable 2.4 MHz operation independent of input voltage and load across 2.5–5.5 V and 0–5 A. Its architecture eliminates ESR dependency, allowing full ceramic capacitor designs.
It integrates an I²C-compatible interface (up to 3.4 Mbps) for dynamic voltage scaling, slew rate programming (0.5–64 mV/µs), PFM enable/disable, and BUCK_EN software control. Hardware enable via EN pin coexists with register-based control, and VSEL pin selects between two preloaded voltage registers (1.02 V and 1.15 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 5 A continuous; supports pulse loads up to 6.5 A only in 05 variant - not applicable to FAN53555BUC18X. |
| Switching Frequency | 2.4 MHz nominal; enables use of compact 330 nH inductor and low-ESR ceramic capacitors (e.g., 44 µF total COUT). |
| 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. |
| Programmable Output | 0.6–1.23 V in 10 mV steps via I²C; hardware-selectable dual defaults: 1.02 V (VSEL = LOW) and 1.15 V (VSEL = HIGH). |
| Quiescent Current | 60 µA typical in PFM mode; drops to <1 µA in shutdown (EN = LOW); critical for battery runtime in always-on subsystems. |
| Package | 20-bump, 1.6 × 2.0 mm Wafer-Level Chip Scale Package (WLCSP); requires microvia PCB layout and solder mask defined pads. |
| Protection Features | Input UVLO (2.4 V threshold), thermal shutdown (150 °C), overcurrent limiting (7.4 A typical peak), and input OVP (6.15 V). |
Pinout & Package
Package: 20-bump WLCSP (1.6 mm × 2.0 mm, 0.4 mm pitch), bottom-side solder balls, no exposed thermal pad.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1 | VSEL | Selects between VSEL0 (1.02 V) and VSEL1 (1.15 V) output defaults; logic-level input referenced to AGND. |
| A2 | EN | Active-high enable; pulls device into <1 µA shutdown when LOW; retains register state except during POR. |
| A3 | SCL | I²C clock input; supports Fast Mode Plus (1 Mbps) and High-Speed Mode (3.4 Mbps) with 100 pF bus capacitance. |
| A4 | VOUT | Output voltage sense node; must connect directly to COUT with minimal trace length and low-inductance path. |
| B1 | SDA | I²C bidirectional data line; open-drain structure requires external pull-up to 1.8 V or 3.3 V. |
| B2–B3, C1–C4 | GND | Power ground for low-side MOSFET and input/output capacitors; multiple parallel connections reduce ground impedance. |
| B4 | AGND | Analog ground reference for internal regulators and I²C interface; must be isolated from high-dV/dt digital return paths. |
| D1–D2, E1–E2 | VIN | Main input power rail (2.5–5.5 V); connects to CIN with shortest possible path to minimize switching noise coupling. |
| D3–D4, E3–E4 | SW | Switching node; connects to inductor; high di/dt node requiring tight loop area and no adjacent signal traces. |
Key Features
| Feature | Design Value |
|---|---|
| Digitally programmable output | 10 mV resolution (0.6–1.23 V range) via I²C; enables dynamic voltage scaling for ARM/Krait processors without hardware changes. |
| PFM/PWM seamless transition | Auto-switches between 60 µA PFM (light load) and fixed 2.4 MHz PWM (heavy load); maintains <±40 mV transient deviation at 100 ns edge. |
| Configurable slew rate | Eight programmable rates (0.5–64 mV/µs) via CONTROL register; prevents overshoot during voltage transitions in sensitive SoC domains. |
| Integrated soft-start & discharge | 300 µs typical startup to regulated VOUT; OUTPUT_DISCHARGE bit enables active VOUT pull-down via internal switch when disabled. |
| Robust protection suite | UVLO (2.4 V), thermal shutdown (150 °C, 17 °C hysteresis), input OVP (6.15 V), and cycle-by-cycle current limiting (7.4 A typical). |
Applications
| Smartphone Application Processor Core | Tablet GPU Power Rail |
|---|---|
Use Scenario: Powers ARM Cortex-A series CPU cores requiring rapid voltage scaling between 0.9 V (idle) and 1.2 V (burst). IC Role / Device Role / Timing Role: Primary core supply regulator with I²C-controlled DVS and sub-100 ns transient response. Use Value: Enables 20%+ battery life extension via precise low-voltage operation and 60 µA quiescent current in PFM mode. |
Use Scenario: Supplies Mali or Adreno GPU cores that dynamically adjust voltage/frequency based on rendering load. IC Role / Device Role / Timing Role: High-current (5 A), fast-transient buck converter synchronized to GPU clock domain via I²C. Use Value: Maintains <±40 mV regulation during 0.3–3 A load steps (100 ns edge), preventing GPU throttling or frame drops. |
| Ultra-Mobile PC SoC I/O Domain | Embedded DSP Power Management |
Use Scenario: Delivers stable 1.02 V or 1.15 V to Intel Atom or Qualcomm Snapdragon I/O voltage rails. IC Role / Device Role / Timing Role: Digitally configurable secondary regulator with hardware VSEL selection and register retention in shutdown. Use Value: Eliminates need for external resistor dividers or discrete voltage-setting components; reduces BOM count by 3 parts. |
Use Scenario: Powers TI C6000 or Analog Devices SHARC DSPs requiring clean, low-noise 1.2 V core supply. IC Role / Device Role / Timing Role: Low-ripple (typ. <15 mVpp), high-PSRR (>40 dB @ 100 kHz) buck regulator with ceramic capacitor compatibility. Use Value: Achieves >85% efficiency at 1.5 A while suppressing switching noise from affecting analog ADC performance. |
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 |
|---|---|---|---|
| TPS62864DRLR | 4 A max, 2.5–5.5 V input, I²C interface, 0.4–1.95 V output (10 mV steps), 1.8 MHz switching, 12-bump 1.2×1.6 mm DSBGA. | Limited to 4 A; lacks VSEL pin for hardware dual-voltage selection; smaller package but lower current capability. | Choose for space-constrained designs where 4 A suffices and dual-hardware-defaults are unnecessary. |
| RTQ2132BWGE | 5 A max, 2.7–5.5 V input, I²C interface, 0.5–1.52 V output (6.25 mV steps), 2.2 MHz switching, 20-pin 2.5×3.0 mm QFN. | Larger QFN package; higher minimum input voltage (2.7 V); tighter 6.25 mV DAC resolution but no VSEL pin. | Prefer when thermal performance demands exposed pad QFN and 2.7–5.5 V system rail alignment is guaranteed. |
Compared with TPS62864DRLR and RTQ2132BWGE, the FAN53555BUC18X uniquely combines 5 A capability, 1.6×2.0 mm WLCSP footprint, hardware VSEL dual-default selection, and 10 mV programmability - making it optimal for high-density mobile SoC core power where board area and flexible voltage sequencing are critical.
Availability
FAN53555BUC18X is available at Aetrix Electronics and suitable for smartphone application processor core supplies, tablet GPU power rails, and ultra-mobile PC SoC I/O domains requiring stable component supply, long-term lifecycle support, and wafer-level packaging compatibility.
Supply support for FAN53555BUC18X 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 FAN53555BUC18X belongs to onsemi's TinyBuck® family of high-efficiency, digitally programmable DC-DC regulators designed specifically for mobile and portable electronics demanding ultra-compact size, fast transient response, and dynamic voltage scaling.
FAQ
What is the default output voltage configuration of the FAN53555BUC18X?
The FAN53555BUC18X is factory-configured with dual hardware-selectable output defaults: 1.02 V when the VSEL pin is driven LOW, and 1.15 V when VSEL is HIGH. These values are stored in VSEL0 and VSEL1 registers respectively and persist through shutdown. The I²C interface allows reprogramming within the 0.6–1.23 V range in 10 mV steps, but the hardware defaults remain unchanged.
Does the FAN53555BUC18X support forced PWM mode, and how is it enabled?
Yes, the FAN53555BUC18X supports forced PWM mode to eliminate frequency variation under light loads. It is enabled by setting the MODE bit (bit 7) to HIGH in the VSEL0 or VSEL1 register via I²C. In forced PWM, quiescent current increases to ~43 mA (vs. 60 µA in PFM), but output ripple and EMI become deterministic and easier to filter - critical for noise-sensitive RF or audio subsystems powered by the same rail.
What is the maximum recommended output capacitance for reliable startup of the FAN53555BUC18X?
The FAN53555BUC18X supports up to ~44 µF total output capacitance (e.g., two 22 µF X5R 0805 capacitors) for stable startup under typical conditions. Exceeding this value - especially with heavy constant-current loads - risks startup failure due to insufficient soft-start current. Equation 1 in the datasheet (COUTMAX ≈ ILIMPK × ILOAD × 320 / VOUT) provides the exact limit; for a 5 A load at 1.02 V, COUTMAX ≈ 1570 µF, but practical layout constraints and transient response favor staying near the 44 µF recommendation.
How does the FAN53555BUC18X handle thermal overload, and what is its shutdown behavior?
The FAN53555BUC18X activates thermal shutdown at a nominal junction temperature of 150 °C, disabling switching until the die cools by 17 °C (hysteresis). During overload, it first engages cycle-by-cycle current limiting; if 16 consecutive current-limit events occur, it enters a 1700 µs fault recovery timeout before attempting soft-start again. This dual-layer protection prevents sustained overheating while allowing automatic recovery after transient overloads - essential for burst-mode workloads in mobile processors.
Can the FAN53555BUC18X be used with input voltages below 2.5 V, such as a partially discharged Li-ion cell?
No - the FAN53555BUC18X has a hard input voltage limit of 2.5 V minimum, enforced by its internal UVLO circuit (2.35–2.45 V threshold). Operating below 2.5 V risks improper gate drive, unstable regulation, or complete dropout. For systems requiring operation down to 2.0 V or lower, a different regulator with extended input range (e.g., TPS62865) must be selected; the FAN53555BUC18X is strictly intended for 2.5–5.5 V rails, such as fully charged single-cell Li-ion (3.0–4.2 V) or USB 3.0 (4.75–5.25 V).
FAN53555BUC18X 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:
- 5A
- 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)
FAN53555BUC18X FAQ
1.How can I place an order for FAN53555BUC18X through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN53555BUC18X 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 FAN53555BUC18X reliable?
The price and inventory of FAN53555BUC18X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN53555BUC18X is usually 5 days.
3.What payment methods are accepted for FAN53555BUC18X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN53555BUC18X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN53555BUC18X?
FAN53555BUC18X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN53555BUC18X 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 FAN53555BUC18X?
For technical support, including FAN53555BUC18X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN53555BUC18X requirements.
6.How does Aetrix verify that FAN53555BUC18X is sourced from the original manufacturer or authorized distributors?
All FAN53555BUC18X 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 FAN53555BUC18X meets industry standards.
7.What is the process for return or replacement of FAN53555BUC18X?
All FAN53555BUC18X units undergo pre-shipment inspection (PSI). If there is an issue with FAN53555BUC18X, 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 FAN53555BUC18X part is unused and in its original packaging.
Return procedure for FAN53555BUC18X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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