Analog Devices Inc. LT3651EUHE-4.2#TRPBF

Overview

LT3651EUHE-4.2#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 4A synchronous step-down Li-ion battery charger IC for single-cell applications, supporting 6.5V–32V input and delivering 4.2V ±0.5% float voltage with 7.5% charge current accuracy, 0.5% float voltage accuracy, and NTC-based temperature monitoring - used in automotive cradle chargers and industrial handheld instruments.

For engineers reviewing the LT3651EUHE-4.2#TRPBF datasheet, LT3651EUHE-4.2#TRPBF pinout, LT3651EUHE-4.2#TRPBF application, or LT3651EUHE-4.2#TRPBF equivalent, key selection criteria include its 36-pin QFN package, programmable 4A charge current, C/10 or timer-based termination, input current limiting via ILIM, and integrated thermal foldback for safe high-current charging in constrained thermal environments.

Technical Context

The LT3651EUHE-4.2#TRPBF implements average current mode control using dual error amplifiers (V-EA and C-EA) to regulate constant-current/constant-voltage charging, with ITH clamping enabling precise 4A max current setting via SENSE–BAT sense resistor voltage (95mV typ). Its synchronous switcher uses bootstrapped high-side drive (BOOST pin) and MOSFET low-side switching for >85% efficiency at 24V_IN/3.9V_BAT.

It integrates autonomous safety logic: preconditioning below 2.9V_BAT, auto-recharge at 97.5% of 4.2V float, bad battery detection after 22.5 min (1/8 of 3-hr timer), and thermal foldback triggered by die temperature rise - all managed without external microcontroller intervention.

Key Specifications

Pinout & Package

LT3651EUHE-4.2#TRPBF is housed in a thermally enhanced 36-pin plastic QFN (UHE package), 5mm × 6mm footprint, 0.75mm profile, with exposed thermal pads at Pin 37 (GND) and Pin 38 (SW) requiring soldering to PCB copper for electrical integrity and thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Li-ion battery charging applications.

Compared with BQ24610RGER and MP2617GQ-Z, the LT3651EUHE-4.2#TRPBF uniquely combines monolithic 4A synchronous switching, programmable input current limiting, dual C/10+timer termination, and integrated NTC monitoring - making it the only option among the three suitable for automotive-grade cradles requiring autonomous, thermally robust, and system-power-aware charging.

Availability

LT3651EUHE-4.2#TRPBF is available at Aetrix Electronics and suitable for automotive cradle chargers, industrial handheld instruments, notebook docking stations, and desktop battery cradles requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for LT3651EUHE-4.2#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, and automotive markets.

The LT3651EUHE-4.2#TRPBF belongs to Linear's Power Management product line, designed specifically for high-efficiency, high-reliability battery charging in wide-input industrial and automotive environments where input transients, thermal constraints, and autonomous safety are critical.

FAQ

What is the exact float voltage setpoint for LT3651EUHE-4.2#TRPBF?

The LT3651EUHE-4.2#TRPBF is factory-trimmed to deliver a nominal 4.2V float voltage with ±0.5% accuracy (4.18V–4.22V) over –40°C to 125°C junction temperature. This matches the standard charging specification for single-cell Li-ion and Li-polymer batteries and is distinct from the LT3651-4.1 variant (4.1V).

Does LT3651EUHE-4.2#TRPBF support both C/10 and timer-based charge termination?

Yes, the LT3651EUHE-4.2#TRPBF supports selectable termination: C/10 detection (when charge current falls to ≤10% of programmed maximum) or user-programmable timer (typically 3 hours with 0.68µF on TIMER pin). The timer can be disabled by grounding the TIMER pin, forcing C/10-only termination.

How does LT3651EUHE-4.2#TRPBF implement input current limiting?

The LT3651EUHE-4.2#TRPBF uses CLP and CLN pins to sense system input current via an external resistor, while the ILIM pin accepts a 0–1V programming voltage. Internally, it regulates charge current downward to maintain the programmed input current limit - enabling stable operation on current-limited sources like USB-C PD or PoE injectors.

What NTC thermistor parameters are compatible with LT3651EUHE-4.2#TRPBF?

The LT3651EUHE-4.2#TRPBF is optimized for a 10kΩ NTC thermistor with B-value 3380K. It sources 50µA, interpreting voltages from 0.29V (≈40°C) to 1.36V (≈0°C); external resistors may be added to scale for alternate B-values, but default operation assumes B3380 at 25°C.

What is the thermal pad configuration for LT3651EUHE-4.2#TRPBF's QFN package?

The LT3651EUHE-4.2#TRPBF uses a 36-pin QFN with two exposed thermal pads: Pin 37 (labeled GND) must be soldered to PCB ground plane for electrical and thermal conduction, and Pin 38 (labeled SW) must be soldered to the high-current switch node copper pour - both are mandatory for rated 4A operation and thermal reliability.