onsemi FAN53555UC13X

Overview

FAN53555UC13X from onsemi is a digitally programmable 5 A synchronous step-down DC-DC regulator with I²C interface, fixed 2.4 MHz switching frequency, and 0.8–1.43 V output range in 10 mV steps. It delivers >80% efficiency from 10 mA to 5 A load, supports 330 nH inductors and low-ESR ceramic capacitors, and targets core voltage regulation for mobile application processors.

For engineers reviewing the FAN53555UC13X datasheet, pinout, applications, or equivalent options, key selection criteria include its 20-bump WLCSP-1.6×2 mm package, programmable slew rate control, PFM/PWM auto-mode transition, 60 µA quiescent current in light-load PFM mode, and hardware/software enable flexibility via EN and BUCK_EN bits.

Technical Context

The FAN53555UC13X employs a proprietary non-linear fixed-frequency PWM modulator with synchronous rectification, maintaining constant 2.4 MHz operation across input voltages (2.5–5.5 V) and load currents (0–5 A). Its architecture eliminates ESR dependency, enabling stable regulation with ceramic output capacitors.

It integrates an I²C-compatible interface supporting up to 3.4 Mbps (High-Speed Mode), allowing dynamic reprogramming of output voltage (via VSEL0/VSEL1 registers), PFM enable/disable, and eight-step slew rate control (0.5–64 mV/µs). The VSEL pin selects between two register banks, with default power-up output set to 1.15 V.

Key Specifications

Pinout & Package

Package: 20-bump Wafer-Level Chip Scale Package (WLCSP), 1.6 mm × 2.0 mm, 0.5 mm pitch, bottom-side solder bumps.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-current, digitally programmable buck regulator applications.

Compared with TPS62933RQYR and MP2174GQZ-P, the FAN53555UC13X uniquely combines 5 A capability, 20-bump WLCSP footprint, 10 mV output resolution, and full I²C configurability-making it the only option for space-constrained, high-performance mobile SoC core regulation requiring real-time voltage agility.

Availability

FAN53555UC13X is available at Aetrix Electronics and suitable for mobile application processor core supply, ultra-mobile PC SoC power, gaming device SoC regulation, and embedded DSP power management requiring stable component supply across design-in, prototyping, and volume production phases.

Supply support for FAN53555UC13X 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 supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The FAN53555UC13X belongs to onsemi's TinyBuck® family of high-density, digitally programmable DC-DC regulators designed specifically for core voltage regulation in battery-powered mobile and ultra-mobile computing platforms.

FAQ

What is the default output voltage of the FAN53555UC13X at power-up?

The FAN53555UC13X powers up with a default output voltage of 1.15 V on both VSEL0 and VSEL1 registers. This is hard-coded per ordering option and confirmed in Table 1 of the datasheet. The VSEL pin selects between these two banks, but for FAN53555UC13X, both defaults are identical. No external programming is required to achieve this initial setting-FAN53555UC13X delivers 1.15 V immediately upon EN assertion and successful soft-start.

Does the FAN53555UC13X support dynamic voltage scaling (DVS) via I²C?

Yes, the FAN53555UC13X fully supports DVS through its I²C interface. It allows real-time reprogramming of the output voltage between 0.8 V and 1.43 V in precise 10 mV increments by writing to the VSEL0 and VSEL1 registers. The FAN53555UC13X also supports programmable slew rate control (eight settings from 0.5 to 64 mV/µs) to manage transition timing and prevent instability during DVS events-critical for ARM/Krait/OMAP processor performance states.

What is the maximum pulse current capability of the FAN53555UC13X?

The FAN53555UC13X is rated for 5 A continuous output current and does not support the 6.5 A pulse current option (which is exclusive to the "05" variant, e.g., FAN53555UC05X). Its peak current limit is 7.4 A typical (ILIMPK, Table 10), but sustained pulses beyond 5 A risk triggering overcurrent protection or thermal shutdown. For applications requiring >5 A burst capability, the FAN53555UC05X-not the FAN53555UC13X-must be selected.

Can the FAN53555UC13X operate with ceramic output capacitors only?

Yes, the FAN53555UC13X is explicitly designed for ceramic output capacitors. Its proprietary control architecture eliminates dependence on output capacitor ESR, enabling stable operation with low-ESR X5R/X7R types. The recommended design uses two 22 µF, 6.3 V, 0805-case X5R capacitors (total 44 µF), as validated in Table 2 and Figure 1. No electrolytic or tantalum capacitors are required or recommended for FAN53555UC13X designs.

What package type and dimensions does the FAN53555UC13X use?

The FAN53555UC13X uses a 20-bump Wafer-Level Chip Scale Package (WLCSP) measuring 1.6 mm × 2.0 mm with 0.5 mm bump pitch. This ultra-compact, bottom-terminal package minimizes PCB area and thermal resistance-ideal for thin mobile devices. Pin configuration follows the standard layout shown in Figure 3 (top view) and Figure 4 (bottom view) of the datasheet, with dedicated VIN, SW, GND, AGND, EN, VSEL, SCL, SDA, and VOUT terminals distributed across the die surface.