onsemi FAN53730UC01X

Overview

FAN53730UC01X from onsemi is a 3 A, constant-on-time (COT) synchronous buck regulator with I²C programmability, supporting 2.3 V–5.5 V input and 0.3 V–2.0 V output. It delivers fast transient response via variable-frequency DCM/CCM operation, features forced CCM control, power-good signaling, and audio reduction mode - optimized for LPDDR memory power in space-constrained mobile SoC designs.

For engineers reviewing the FAN53730UC01X datasheet, pinout, applications, or equivalent options, key selection criteria include its 12-bump WLCSP package, I²C address 0x22, dual VSET defaults (1.00 V / 1.05 V), 2.5 MHz CCM switching, and integrated valley current limiting (4.6 A typ) with thermal/UVLO/short-circuit protection.

Technical Context

The FAN53730UC01X implements a constant-on-time control architecture that dynamically adjusts switching frequency based on load: operating in discontinuous conduction mode (DCM) at light loads for ultra-low quiescent current (12.8 µA typ), and transitioning to continuous conduction mode (CCM) at higher loads with fixed ~2.5 MHz frequency under FCCM enable. Its valley-current sensing loop regulates output by clamping inductor valley current to programmable thresholds (4.6 A or 2.3 A).

I²C interface enables full configuration including dynamic voltage scaling (8 slew rates), power-good polarity inversion, output discharge disable, and audio reduction timeout (25 µs or 40 µs). The device supports seamless VSEL toggling between two preprogrammed outputs (1.00 V and 1.05 V) without requiring external resistors or reconfiguration of control registers.

Key Specifications

Pinout & Package

Package: 12-bump WLCSP (1.07 mm × 1.36 mm, 0.35 mm pitch, Case 567GK), bottom-side bump layout with thermal pad connected to GND.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Compared with TPS6286410RQYR and RTQ2134BGQW, the FAN53730UC01X uniquely combines I²C-configurable DVS, audio-noise suppression, and dual-VSET hardware toggling in a 1.07×1.36 mm WLCSP - making it optimal for mobile SoC power islands demanding both precision and acoustic silence.

Availability

FAN53730UC01X is available at Aetrix Electronics and suitable for LPDDR memory power, mobile processor core rails, RF transceiver biasing, and ultra-low-power sensor hub designs requiring stable component supply and long-term production continuity.

Supply support for FAN53730UC01X 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 focused on energy-efficient innovation, delivering silicon solutions for automotive, industrial, cloud, and intelligent edge applications.

The FAN53730UC01X belongs to onsemi's high-efficiency, ultra-compact DC-DC converter product line - engineered specifically for advanced mobile and wearable platforms requiring sub-2 mm² footprint, I²C configurability, and acoustic-noise mitigation.

FAQ

What is the I²C address of the FAN53730UC01X?

The FAN53730UC01X uses a fixed 7-bit I²C address of 0x22 (binary 0100010), as specified in the Ordering Information table on page 2 of the datasheet. This address is factory-programmed and not user-modifiable. Communication requires standard Fast Mode Plus timing (1 MHz SCL), with SDA/SCL pins pulled up to VI/O (1.2 V or 1.8 V compatible). The FAN53730UC01X responds only to this address during read/write operations to its internal register map.

Does the FAN53730UC01X support dynamic voltage scaling (DVS)?

Yes, the FAN53730UC01X supports full dynamic voltage scaling via its I²C interface. DVS is enabled using Register 06h bit [4], and the ramp rate is set via RR_DVS bits [4:2] in Register 02h - offering eight programmable dwell times from 2 s/step to 16 s/step. Each step changes VOUT by 10 mV, allowing smooth, controlled transitions between voltage levels such as 0.85 V → 1.1 V for CPU performance scaling. The FAN53730UC01X executes DVS autonomously after register writes, without host intervention per step.

What are the default VSET voltages programmed into the FAN53730UC01X?

The FAN53730UC01X is factory-programmed with VSET1 = 1.00 V and VSET2 = 1.05 V, as confirmed in the Ordering Information table (page 2). These values are stored in nonvolatile configuration registers and persist across power cycles. VSEL pin logic level selects between them: low for 1.00 V, high for 1.05 V. Unlike logic-controlled variants, these defaults are immutable and cannot be overwritten via I²C - ensuring consistent dual-rail behavior in systems using hardware-based voltage selection.

How does the Audio Reduction Mode (ARM) function in the FAN53730UC01X?

Audio Reduction Mode (ARM) in the FAN53730UC01X eliminates audible noise from ceramic capacitors by enforcing a minimum switching frequency of either 25 kHz or 40 kHz. When enabled (ARM_EN = 1 in Register 06h[5]), the device monitors idle time between switching events. If idle time exceeds the ARM timeout (25 µs or 40 µs, set via ARM_TO in Register 02h[6]), the low-side FET is forced on to discharge VOUT slightly, triggering a new switching cycle. This ensures no frequency components fall within the human-audible range (20 Hz–20 kHz), directly addressing noise complaints in consumer handsets and wearables.

What thermal resistance values apply to the FAN53730UC01X in its WLCSP package?

The FAN53730UC01X in 12-bump WLCSP (Case 567GK) has θ_JA = 130°C/W on a 2s2p PCB without via-in-pad, and θ_JB = 50°C/W with via-in-pad - per JEDEC JESD51 testing conditions. These values assume proper thermal pad soldering to a solid GND plane. At 3 A load and 3.8 V input, typical power dissipation is ~350 mW; thus, junction temperature rise above ambient is ~45°C without vias and ~17°C with vias. To maintain T_J ≤ 125°C at +85°C ambient, thermal vias under the package are strongly recommended.