onsemi FAN4868UC33X

Overview

FAN4868UC33X from onsemi is a synchronous boost DC-DC regulator IC designed to generate a stable 3.3 V output from a single-cell Li-ion battery (2.3 V–3.2 V input), delivering up to 300 mA at VIN = 2.7 V, featuring integrated N-channel boost switch and P-channel synchronous rectifier, 3 MHz switching frequency, and true load disconnect in shutdown mode. It targets space-constrained portable power rails requiring high efficiency and ultra-low quiescent current.

For engineers reviewing the FAN4868UC33X datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed 3.3 V output accuracy (±3.5% over temperature), 6-bump WLCSP package (0.4 mm pitch), light-load PFM operation with 37 µA quiescent current, thermal/overcurrent protection, and compatibility with 0402/0603 passive footprints.

Technical Context

The FAN4868UC33X employs a minimum on-time / computed minimum off-time current-mode control architecture operating at ~3 MHz in PWM CCM mode under moderate-to-heavy loads, automatically transitioning to variable-frequency PFM for light loads to maintain regulation with <37 µA quiescent current. Its internal synchronous rectifier eliminates external diode requirements and enables true load disconnect during shutdown.

Startup includes three-phase sequencing-LIN (linear charging), SS (soft-start with ramped current limit), and BST (normal boost)-with fault detection on startup failure, sustained current limiting, or short-circuit collapse. Thermal shutdown triggers at 150 °C with 30 °C hysteresis, and UVLO activates at 2.3 V with 190 mV hysteresis.

Key Specifications

Pinout & Package

Package: Wafer-Level Chip Scale Package (WLCSP), 6-bump, 0.4 mm pitch, case 567VM, dimensions 0.88 × 1.23 × 0.458 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with FAN4868UC33X, TPS61099YFFR offers broader input compatibility but sacrifices switching speed and compactness, while MAX17222ELT+T extends low-VIN capability and current capacity at the cost of larger package and higher shutdown IQ-making FAN4868UC33X optimal for space-constrained, single-cell Li-ion systems prioritizing 3 MHz efficiency and minimal footprint.

Availability

FAN4868UC33X is available at Aetrix Electronics and suitable for smartphone core power, portable media player rails, PDA SoC supplies, and portable instrument sensor bias requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for FAN4868UC33X 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The FAN4868UC33X belongs to onsemi's TinyBoost™ family of ultra-compact synchronous boost regulators, engineered specifically for single-cell Li-ion battery systems in ultra-thin portable electronics where minimal footprint, high efficiency, and low quiescent current are critical.

FAQ

What is the guaranteed maximum output current for FAN4868UC33X at 2.3 V input?

The FAN4868UC33X guarantees a maximum output current of 250 mA at VIN = 2.5 V and 200 mA at VIN = 2.3 V, per Table 6 of the datasheet. These values reflect worst-case conditions across −40°C to +85°C ambient temperature and account for output voltage accuracy and thermal derating. The device achieves this while maintaining 3.3 V output within ±3.5% tolerance and sustaining 92% peak efficiency at higher input voltages. FAN4868UC33X is not rated for continuous 300 mA operation below VIN = 2.5 V.

Does FAN4868UC33X require an external diode for synchronous rectification?

No, FAN4868UC33X does not require an external diode. It integrates both an N-channel boost switch and a P-channel synchronous rectifier, eliminating the need for an external Schottky diode. This integration reduces conduction losses, improves efficiency (up to 92%), and simplifies the bill of materials. The internal synchronous rectifier also enables true load disconnect during shutdown, preventing reverse current flow from VOUT to VIN. FAN4868UC33X is explicitly designed for diode-less operation in its typical application circuit.

What is the shutdown current specification for FAN4868UC33X?

The shutdown current for FAN4868UC33X is specified as 0.5 µA typical and 1.5 µA maximum at VIN = 2.7 V and TA = −40°C to +85°C, per Table 6 of the datasheet. This ultra-low leakage ensures minimal battery drain during system sleep modes. The device achieves true load disconnect in shutdown, with VOUT leakage current limited to 10 nA and reverse VIN-to-VOUT leakage capped at 2.5 µA. FAN4868UC33X maintains this performance across its full operating temperature range without external biasing.

Can FAN4868UC33X operate with a 2.2 µF input capacitor and 4.7 µF output capacitor in 0402/0603 packages?

Yes, FAN4868UC33X is validated to operate with a 2.2 µF X5R 0402 input capacitor (CIN) and a 4.7 µF X5R 0603 output capacitor (COUT), as specified in Table 8 of the datasheet. These values meet the minimum effective capacitance (CEFF ≥ 1.5 µF) requirement for stability across 2.3–4.5 V input and 0–200 mA load. The 0603 COUT is recommended for best transient response and reduced ripple; a 6.3 V-rated variant is acceptable, though 10 V rating enhances DC bias performance. FAN4868UC33X's stability guarantee covers these exact component selections.

What protection features are built into FAN4868UC33X?

FAN4868UC33X includes thermal shutdown (150 °C trip point with 30 °C hysteresis), cycle-by-cycle overcurrent protection (650–950 mA peak switch current limit), under-voltage lockout (2.3 V turn-on with 190 mV hysteresis), and automatic fault recovery after 480 clock cycles. It also provides true load disconnect in shutdown, limiting reverse leakage to <10 nA. These protections are fully integrated and require no external components. FAN4868UC33X enters a high-impedance state during fault conditions and autonomously restarts once the fault clears, ensuring robust operation in portable systems.