Analog Devices Inc. LTC4055EUF-1#PBF

Overview

LTC4055EUF-1#PBF 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, and integrates ideal diode operation for seamless battery-to-load switchover in portable USB devices like MP3 players and PDAs.

For engineers reviewing the LTC4055EUF-1#PBF datasheet, LTC4055EUF-1#PBF pinout, LTC4055EUF-1#PBF application, or LTC4055EUF-1#PBF equivalent, key selection considerations include its NTC thermistor interface for temperature-qualified charging, programmable charge current (up to 1A) and termination timer, thermal regulation at 105°C, and 16-pin 4mm × 4mm QFN package with exposed thermal pad.

Technical Context

The LTC4055EUF-1#PBF implements load-dependent charging: it dynamically reduces battery charge current as system load current increases to maintain strict USB input compliance (100mA or 500mA). Its dual-path architecture separates IN1/IN2-to-OUT power delivery from IN1/IN2-to-BAT and OUT-to-BAT charging paths, enabling wall adapter support via WALL pin detection and ACPR output signaling.

It features a precision constant-current/constant-voltage linear charger with 4.1V float voltage (LTC4055-1 variant), automatic trickle-charge below 2.8V, recharge threshold at VFLOAT − 100mV, and thermal feedback limiting that caps junction temperature at 105°C. The integrated ideal diode provides <100mV forward drop at 400mA while blocking reverse current.

Key Specifications

Pinout & Package

Package: 16-lead (4mm × 4mm) plastic QFN with exposed thermal pad (Pin 17), rated for –40°C to +85°C operation. Exposed pad must be soldered to PCB ground for thermal and electrical integrity.

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 BQ24075RGER and LTC4054EDD-4.2#TRMPBF, the LTC4055EUF-1#PBF uniquely combines USB-compliant input limiting, dual-source charging (USB + wall), NTC-based thermal safety, and seamless ideal diode switchover in a single 4mm × 4mm QFN - making it the only option for compact, safety-critical, multi-source portable systems.

Availability

LTC4055EUF-1#PBF is available at Aetrix Electronics and suitable for USB-powered portable audio devices, handheld medical monitors, industrial scanners, and PDAs requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature range operation.

Supply support for LTC4055EUF-1#PBF 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 continues to develop and support its precision analog and power management portfolio.

The LTC4055EUF-1#PBF belongs to Linear's PowerPath™ family, designed specifically for USB-powered portable electronics requiring intelligent power routing, battery safety, and seamless source transition without firmware intervention.

FAQ

What is the key functional difference between LTC4055EUF-1#PBF and the standard LTC4055EUF#PBF?

The LTC4055EUF-1#PBF features a 4.1V float voltage with ±0.8% accuracy, optimized for improved battery longevity and high-temperature safety margin, whereas the standard LTC4055EUF#PBF uses 4.2V. This 100mV reduction lowers stress on the cathode material during float, particularly beneficial in applications operating above 40°C ambient or requiring extended cycle life - both variants share identical pinout, PowerPath™ architecture, and all other specifications.

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

The LTC4055EUF-1#PBF enforces USB compliance through load-dependent charging: it continuously monitors system load current (IOUT) and dynamically reduces battery charge current (IBAT) so that IIN = IOUT + IBAT never exceeds the selected limit (100mA or 500mA). This real-time current arbitration is hardware-based and requires no microcontroller intervention, ensuring robust adherence to USB 2.0 power specifications under all operating conditions.

Can the LTC4055EUF-1#PBF charge a battery while powering the system from a wall adapter connected to the OUT pin?

Yes. When a wall adapter raises the WALL pin above 1V, the LTC4055EUF-1#PBF disables the IN1/IN2-to-OUT path and enables OUT-to-BAT charging - allowing the wall adapter to simultaneously power the system load and charge the battery. This functionality is confirmed in the datasheet's "Output Powered Charger" mode table and operational state diagram, and requires no external FETs or control logic.

What is the purpose of the exposed thermal pad (Pin 17) on the LTC4055EUF-1#PBF QFN package?

The exposed thermal pad (Pin 17) on the LTC4055EUF-1#PBF is electrically and thermally connected to internal GND. It must be soldered to a PCB copper pour tied to system ground to achieve θJA = 37°C/W and sustain full 1A charge current without exceeding the 125°C maximum junction temperature. Omitting this connection degrades thermal performance and may trigger premature thermal regulation or failure.

Does the LTC4055EUF-1#PBF support temperature-qualified charging, and how is it implemented?

Yes. The LTC4055EUF-1#PBF supports temperature-qualified charging via dedicated VNTC (Pin 15) and NTC (Pin 16) pins. VNTC supplies a 3.8V bias to an external resistor-thermistor divider; the NTC pin compares the resulting voltage against cold (0.74×VVNTC) and hot (0.29×VVNTC) thresholds. If either threshold is breached, charging suspends - but the timer is preserved - and resumes automatically when temperature returns to the safe window.