onsemi FAN53601AUC18X

Overview

FAN53601AUC18X from onsemi is a 6 MHz, 1 A synchronous buck regulator in WLCSP-6 package delivering fixed 1.800 V output from 2.3–5.5 V input, featuring 24 µA quiescent current, internal soft-start, and forced PWM/external sync capability - deployed in ultra-compact mobile power rails for application processors and RF modules.

For engineers reviewing the FAN53601AUC18X datasheet, pinout, applications, or equivalent options, key selection criteria include its 6 MHz switching frequency enabling 470 nH inductors, PFM/PWM auto-mode transition behavior, active output discharge option, thermal shutdown at 150°C, and WLCSP-6 layout constraints for high-density PCBs.

Technical Context

The FAN53601AUC18X uses a proprietary non-linear fixed-frequency PWM modulator with synchronous rectification, maintaining 6 MHz operation across wide VIN (2.3–5.5 V) and IOUT (0–1 A) ranges while decoupling switching frequency from load and input variations via an internal frequency loop.

It supports three operating modes: auto PFM/PWM (MODE = 0 V), forced PWM (MODE = HIGH), and external clock synchronization (square wave 1.3–1.7 MHz on MODE pin, yielding 5.2–6.8 MHz switching). Its current-limit protection triggers hiccup-mode restart after 16 cycles of overcurrent, with thermal shutdown at 150°C and 15°C hysteresis.

Key Specifications

Pinout & Package

Package: Wafer-Level Chip-Scale Package (WLCSP-6), 0.4 mm pitch, 1.160 mm × 0.860 mm footprint, 586 µm typical height, bumps facing down in standard mounting.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS62260DRVR and RT7290AZSP, the FAN53601AUC18X delivers higher current (1 A vs. 600 mA/1 A), superior light-load efficiency (24 µA vs. ~50 µA), integrated sync capability, and active discharge - making it optimal for space-constrained, battery-sensitive, and EMI-managed designs.

Availability

FAN53601AUC18X is available at Aetrix Electronics and suitable for mobile computing, RF front-end power, and industrial IoT applications requiring stable component supply, consistent WLCSP-6 packaging, and guaranteed 1.800 V output accuracy.

Supply support for FAN53601AUC18X 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 focused on energy-efficient electronics, with leadership in power management, analog, sensor, and connectivity solutions.

The FAN53601AUC18X belongs to onsemi's high-frequency synchronous buck regulator product line, engineered specifically for compact, high-efficiency power delivery in portable and wireless devices where board area and battery life are critical.

FAQ

What is the output voltage tolerance of the FAN53601AUC18X over full load and temperature?

The FAN53601AUC18X delivers a fixed 1.800 V output with ±3.7% tolerance (1.732–1.868 V) across 0–1 A load and −40°C to +85°C ambient temperature, as specified in the Electrical Characteristics table under "1.800 V" row with I_LOAD = 0 to 1 A conditions. This includes both line and load regulation effects, verified in closed-loop operation.

Does the FAN53601AUC18X support external clock synchronization, and what frequency range is accepted?

Yes, the FAN53601AUC18X supports external clock synchronization via its MODE pin. A square wave input between 1.3 MHz and 1.7 MHz is accepted, and the internal switching frequency locks to exactly four times the applied frequency - yielding a synchronized range of 5.2–6.8 MHz. The MODE pin includes Schmitt-trigger buffering to tolerate slow edges.

Is active output discharge enabled on the FAN53601AUC18X, and how does it function?

Yes, active output discharge is enabled on the FAN53601AUC18X. When EN is pulled low, an internal 230 Ω resistor discharges the FB node to GND, rapidly collapsing the output voltage. This feature ensures clean power-down sequencing and eliminates residual hold-up voltage that could interfere with downstream logic or cause latch-up in multi-rail systems.

What is the minimum input voltage required for the FAN53601AUC18X to maintain 6 MHz switching at full 1 A load?

The FAN53601AUC18X maintains 6 MHz switching at full 1 A load only when VIN ≥ 2.7 V. Below this, the minimum off-time (t_OFF(MIN) = 40 ns) limits achievable duty cycle, causing switching frequency to drop - as shown in Figure 34. At VIN = 2.3 V and 1 A, frequency falls to ~4.5 MHz in PWM mode.

How does the FAN53601AUC18X handle overload or short-circuit conditions?

The FAN53601AUC18X employs cycle-by-cycle current limiting followed by hiccup-mode fault recovery. Upon reaching peak current limit (1.5–2.0 A open-loop), it disables switching for ~1.3 ms, then attempts restart. If the fault persists (e.g., hard short), it repeats this cycle with <15% duty, limiting average power dissipation and preventing thermal runaway.