onsemi FAN48630UC35X

Overview

FAN48630UC35X from onsemi is a synchronous boost regulator with integrated power FETs, designed for single-cell Li-ion battery systems requiring 3.5 V fixed output at up to 1500 mA load current. It features true bypass mode, 2.5 MHz switching frequency, and low-quiescent-current forced bypass (4–10 µA) for extended battery life in portable electronics.

For engineers reviewing the FAN48630UC35X datasheet, pinout, applications, or equivalent options, key selection considerations include input voltage range (2.35–5.5 V), output accuracy (±4%), thermal shutdown thresholds (120 °C/100 °C hysteresis), soft-start timing (600 µs fast mode), and WLCSP-16 package compatibility with high-density PCB layouts.

Technical Context

The FAN48630UC35X operates in current-mode control with valley-current limiting and supports seamless transitions between continuous conduction mode (CCM) at 2.5 MHz and discontinuous conduction mode (DCM) at light loads. Its modulator logic manages four operating states: Linear Startup (LIN), Soft-Start (SS), Boost (BST), and Bypass (BPS), triggered by VIN relative to VOUT_TARGET and load conditions.

Bypass functionality is implemented via dual internal P-channel MOSFETs (Q1 and Q3), enabling sub-100 mΩ path resistance when VIN exceeds 3.5 V + 25 mV hysteresis. Forced Bypass Mode disables most bias circuitry except short-circuit protection (OCP On variant) or deactivates protections (Low IQ variant), depending on part suffix - FAN48630UC35X uses Low IQ configuration.

Key Specifications

Pinout & Package

Package: 16-bump Wafer-Level Chip-Scale Package (WLCSP), 1.78 × 1.78 × 0.586 mm, 0.4 mm pitch, case 567SY.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS61291DRVR and MAX17222ETA+T, the FAN48630UC35X uniquely combines 1500 mA capability, true bypass, VSEL-driven transient headroom control, and open-drain PG - making it optimal for battery-powered systems requiring robust brownout immunity and dynamic power management.

Availability

FAN48630UC35X is available at Aetrix Electronics and suitable for USB OTG power supplies, smartphone brownout prevention circuits, and boosted audio amplifier rails requiring stable component supply across production lifecycles.

Supply support for FAN48630UC35X 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 (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The FAN48630UC35X belongs to the TINYBOOST® family of compact, high-frequency boost regulators engineered specifically for space-constrained portable electronics powered by advanced Li-ion batteries.

FAQ

What is the exact output voltage setting for FAN48630UC35X?

The FAN48630UC35X is factory-configured for dual-setpoint output: nominal 3.50 V with ±2% accuracy and a secondary target of 3.70 V. The VSEL pin allows dynamic selection between these points during operation to improve transient response without changing external components. This dual-voltage capability is confirmed in Table 1 of the official datasheet (FAN48630/D, Rev. 3, May 2024).

Does FAN48630UC35X support true bypass mode, and how is it activated?

Yes, the FAN48630UC35X supports true bypass mode both automatically and forcibly. Automatic bypass engages when VIN exceeds the target VOUT (3.5 V) plus 25 mV hysteresis and no switching has occurred for 5 seconds. Forced bypass is activated by pulling the BYP pin LOW, which places the device into ultra-low-IQ state (4–10 µA) while maintaining a low-resistance path from VIN to VOUT. Both modes are documented in the "Bypass Operation" section of the datasheet.

What package type and dimensions does FAN48630UC35X use?

The FAN48630UC35X uses a 16-bump Wafer-Level Chip-Scale Package (WLCSP) with 0.4 mm pitch, measuring 1.78 × 1.78 × 0.586 mm (case 567SY). Pin mapping follows a 4×4 bump array with specific assignments for EN, PG, VIN, VSEL, AGND, VOUT, BYP, SW, and PGND as shown in Figure 3 and Table 3 of the datasheet. This compact footprint supports high-density mobile PCB designs.

How does the soft-start behavior differ between FAN48630UC35X and slower variants like FAN48630UC45X?

The FAN48630UC35X uses the FAST soft-start option, achieving regulation in 600 µs with doubled LIN1/LIN2 phase currents versus SLOW variants. In contrast, FAN48630UC45X uses SLOW soft-start (1300 µs) to limit inrush current. This distinction is explicitly defined in Table 1's "Soft-Start" column and impacts system wake-up latency and input capacitor sizing requirements for the FAN48630UC35X.

What protection features are active in Forced Bypass Mode for FAN48630UC35X?

In Forced Bypass Mode, the FAN48630UC35X (Low IQ variant) disables short-circuit, UVLO, OVP, and overtemperature protections to minimize quiescent current. Only the basic conduction path remains active. This behavior is specified in the "Forced Bypass" subsection of the datasheet and differentiates it from OCP-On variants like FAN48630UC45X, where short-circuit protection remains enabled during bypass.