onsemi FAN1086M285X

Overview

FAN1086M285X from Fairchild Semiconductor is a fixed-output 2.85V, 1.5A low-dropout linear regulator in TO-263 package, optimized for SCSI active terminators and motherboard clock supplies with 1.5V dropout at full load, ±2% output voltage tolerance, and on-chip thermal shutdown.

For engineers reviewing the FAN1086M285X datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage under 1.5V at 1.5A, thermal resistance of 3°C/W (junction-to-case), fixed 2.85V output accuracy, and compatibility with standard PCB layout practices for TO-263 power packages.

Technical Context

The FAN1086M285X implements a PNP-based LDO architecture with trimmed current limit and internal thermal limiting, enabling stable operation up to 125°C junction temperature. Its reference voltage is 1.25V with ±2% tolerance, and output is set by internal resistor network for precise 2.85V regulation without external components.

It delivers 1.5A output with load regulation of 0.05% typical and line regulation of 0.2% max, supporting transient response-critical applications where input voltage may dip as low as 4.35V. Ripple rejection reaches 72dB at 120Hz with 22µF tantalum output capacitor.

Key Specifications

Pinout & Package

TO-263 (D²PAK) thermally enhanced surface-mount package with exposed tab connected to V_OUT; requires minimum 0.5 in² copper area on backside ground plane for rated thermal performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with LM1086CT-2.85/NOPB and TPS7A4701RGWR, the FAN1086M285X offers superior thermal performance (3°C/W vs. 5°C/W), lower dropout (1.5V vs. 1.7V), and factory-trimmed 2.85V output-making it uniquely suited for high-reliability SCSI termination and dense motherboard power delivery where layout space and thermal headroom are constrained.

Availability

FAN1086M285X is available at Aetrix Electronics and suitable for SCSI termination systems, motherboard clock supplies, battery charger references, and post-regulation of switching supplies requiring stable component supply and long-term industrial availability.

Supply support for FAN1086M285X 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

Fairchild Semiconductor was a U.S.-based analog and power IC manufacturer, acquired by ON Semiconductor in 2016; known for high-performance power management and interface solutions.

The FAN1086 series was designed specifically for low-voltage, high-current linear regulation in computing and storage infrastructure, emphasizing dropout minimization, thermal robustness, and SCSI-compliant fixed outputs.

FAQ

What is the maximum input voltage rating for the FAN1086M285X?

The FAN1086M285X has an absolute maximum input voltage of 7.5V. Operation above this level risks permanent damage. For reliable 2.85V output, the minimum recommended input is 4.35V to maintain regulation under full 1.5A load, per its specified dropout behavior. Always observe derating guidelines for thermal safety at elevated ambient temperatures.

Does the FAN1086M285X require external components to regulate at 2.85V?

No, the FAN1086M285X is a fixed-output variant with internal resistor network calibrated to deliver 2.85V ±2%. Only input and output capacitors are required: ≥10µF at VIN and ≥22µF tantalum (or low-ESR ceramic equivalent) at VOUT. No external feedback resistors or adjustment pins are needed, simplifying layout for SCSI termination and clock supply designs.

How does the thermal shutdown feature operate in the FAN1086M285X?

The FAN1086M285X activates thermal shutdown at 155°C junction temperature and remains latched off until junction cools by 10°C (hysteresis), resuming regulation at ~145°C. This protects against sustained overloads or inadequate heatsinking. The TO-263 package's 3°C/W θ_JC enables rapid heat transfer to PCB copper, allowing safe continuous operation at 1.5A with proper board-level thermal design.

Can the FAN1086M285X be used in place of the adjustable FAN1086 version?

No-the FAN1086M285X is a fixed-output device with no ADJ pin; it cannot replace the adjustable FAN1086 (which uses external resistors to set output). Substituting them requires redesigning the feedback network and verifying stability. The FAN1086M285X is intended for applications needing factory-trimmed 2.85V, such as SCSI termination, where precision and simplicity outweigh adjustability.

What is the typical ripple rejection performance of the FAN1086M285X at high frequencies?

The FAN1086M285X achieves 72dB ripple rejection at 120Hz with a 22µF tantalum output capacitor. At higher frequencies, rejection degrades: ~60dB at 1kHz and ~40dB at 100kHz. For best high-frequency noise suppression, pair it with a small ceramic capacitor (e.g., 100nF) in parallel with the main output cap, placed close to the FAN1086M285X output pin.