Analog Devices Inc. LTC4055EUF-1#TRPBF

Overview

LTC4055EUF-1#TRPBF from Analog Devices (formerly Linear Technology) is a USB-compliant PowerPath™ controller and single-cell Li-ion battery charger IC. It delivers 4.1V float voltage with ±0.8% accuracy, supports 100mA/500mA input current limit selection via HPWR pin, integrates ideal diode operation (≤100mV forward drop at 400mA), and features NTC thermistor-based temperature-qualified charging for portable USB devices like MP3 players and PDAs.

For engineers reviewing the LTC4055EUF-1#TRPBF datasheet, LTC4055EUF-1#TRPBF pinout, LTC4055EUF-1#TRPBF application, or LTC4055EUF-1#TRPBF equivalent, key selection considerations include its 4.1V fixed float voltage (vs. 4.2V in LTC4055), thermal regulation at 105°C, programmable charge current (up to 1A), and QFN-16 (4mm × 4mm) package with exposed thermal pad.

Technical Context

The LTC4055EUF-1#TRPBF implements dual-path power management: it regulates input current from USB VBUS (IN1/IN2) while dynamically allocating remaining current to battery charging (BAT), ensuring strict USB compliance. Its PowerPath architecture enables seamless switchover between USB supply and battery without output droop-maintaining VOUT within 100mV of VBAT via integrated ideal diode control.

Charging follows constant-current/constant-voltage (CC/CV) profile with 4.1V float voltage, 2.8V trickle-charge threshold, and automatic recharge at 100mV below float. Temperature qualification uses VNTC-biased NTC network with cold/hot fault thresholds at 0.74×VVNTC and 0.29×VVNTC, respectively, and includes thermal shutdown at 125°C junction temperature.

Key Specifications

Pinout & Package

Package: 16-lead (4mm × 4mm) plastic QFN with exposed thermal pad (Pin 17 = GND, must be soldered to PCB).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar USB power management and Li-ion charging applications.

Compared with MAX1555ETE+ and BQ24075RGTR, the LTC4055EUF-1#TRPBF uniquely combines 4.1V float voltage for enhanced battery life, dedicated NTC fault detection with hysteresis, and active wall adapter sensing with ACPR signaling-making it optimal for medical and industrial USB peripherals requiring robust thermal and power-source management.

Availability

LTC4055EUF-1#TRPBF is available at Aetrix Electronics and suitable for USB-powered portable audio, handheld medical diagnostics, industrial PDAs, and smart sensor nodes requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to +85°C operation.

Supply support for LTC4055EUF-1#TRPBF 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

Analog Devices acquired Linear Technology in 2017 and maintains its precision analog and power management portfolio with rigorous automotive and industrial qualification standards.

The LTC4055EUF-1#TRPBF belongs to Linear's PowerPath™ USB power management family, designed specifically for portable battery-powered USB peripherals needing compliant current limiting, seamless source switchover, and temperature-safe Li-ion charging.

FAQ

What is the exact float voltage of the LTC4055EUF-1#TRPBF and how does it differ from the standard LTC4055?

The LTC4055EUF-1#TRPBF has a preset float voltage of 4.100V ±0.8%, optimized for improved battery cycle life and high-temperature safety margin. This differs from the standard LTC4055, which uses 4.200V ±0.8%. The -1 suffix explicitly denotes this lower voltage variant, and the specification is fully guaranteed over –40°C to +85°C.

How does the LTC4055EUF-1#TRPBF ensure USB compliance during simultaneous charging and system operation?

The LTC4055EUF-1#TRPBF enforces USB current limits by dynamically reducing battery charge current as system load current increases-keeping total input current (IIN = IOUT + IBAT) ≤100mA or ≤500mA depending on HPWR pin state. This load-dependent charging is implemented in hardware and requires no microcontroller intervention.

Can the LTC4055EUF-1#TRPBF be used without an NTC thermistor?

Yes. To disable NTC functionality, tie the NTC pin directly to GND. This disables all temperature monitoring-including cold/hot fault detection and timer suspension-but preserves full charging, PowerPath control, and USB compliance functions of the LTC4055EUF-1#TRPBF.

What is the purpose of the ACPR pin on the LTC4055EUF-1#TRPBF and how is it used?

The ACPR (Wall Adapter Present) pin is an active-low open-drain output that signals wall adapter detection. It pulls low when WALL pin voltage exceeds 1.0V and either IN1/IN2 or OUT is above UVLO (≥3.8V). System firmware uses ACPR to trigger power-source prioritization or UI indicators-enabling intelligent fallback behavior in dual-supply designs using the LTC4055EUF-1#TRPBF.

Does the LTC4055EUF-1#TRPBF support charging from a wall adapter connected to the OUT pin?

Yes. When a wall adapter applies voltage to the OUT pin (with WALL pin pulled >1.0V), the LTC4055EUF-1#TRPBF disables the IN1/IN2-to-OUT path and enables OUT-to-BAT charging-allowing the battery to charge from the wall source while powering the system. This is a core PowerPath feature confirmed in the LTC4055EUF-1#TRPBF datasheet's operational modes table.