Analog Devices Inc. LT3650IMSE-4.2#TRPBF

Overview

LT3650IMSE-4.2#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 2A step-down Li-Ion/Polymer battery charger IC with 4.75V–32V input range, 4.2V float voltage, and integrated 2A switch. It delivers constant-current/constant-voltage charging with C/10 or programmable 3-hour timer termination, preconditioning for deeply discharged batteries, and NTC-based temperature monitoring - used in 12V–24V automotive cradle chargers and industrial handheld instruments.

For engineers reviewing the LT3650IMSE-4.2#TRPBF datasheet, LT3650IMSE-4.2#TRPBF pinout, LT3650IMSE-4.2#TRPBF application, or LT3650IMSE-4.2#TRPBF equivalent, key selection considerations include its 4.2V fixed float voltage, MSOP-12 package with exposed thermal pad, 1MHz average current mode control, CLP-based system current limiting, and binary open-collector status outputs (CHRG/FAULT).

Technical Context

The LT3650IMSE-4.2#TRPBF implements a fixed-frequency (1MHz) average current mode buck regulator architecture with internal 2A switch and bootstrapped gate drive (BOOST pin). Its control loop directly regulates average inductor current via SENSE–BAT differential voltage, while independently monitoring BAT voltage for CV transition and auto-restart at 97.5% of V_FLT.

It integrates dual termination schemes: C/10 detection (V_SENSE–BAT = 10mV ±2.5mV) and user-programmable timer (CTIMER = 0.68µF → 3h full cycle), with bad-battery detection triggered if preconditioning exceeds 22.5 minutes. The RNG/SS pin enables dynamic charge current scaling and soft-start via 50µA current source.

Key Specifications

Pinout & Package

LT3650IMSE-4.2#TRPBF is housed in a 12-lead plastic MSOP package (3mm × 4.9mm) with exposed thermal pad (Pin 13 = SGND), optimized for thermal dissipation in high-current charging applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Li-Ion battery charger applications.

Compared with LT3652IMSE-4.2#TRPBF and BQ24610RGER, the LT3650IMSE-4.2#TRPBF delivers optimal balance of integration, thermal performance, and ease of use for fixed-input industrial and automotive chargers - eliminating external switches while maintaining precision float regulation and robust fault handling.

Availability

LT3650IMSE-4.2#TRPBF is available at Aetrix Electronics and suitable for automotive cradle chargers, industrial handheld instruments, desktop docking stations, and notebook auxiliary chargers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LT3650IMSE-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 industrial, automotive, communications, and healthcare markets.

The LT3650IMSE-4.2#TRPBF belongs to Linear's high-voltage monolithic battery charger product line, designed specifically for robust, low-component-count charging solutions in 12V–24V industrial and automotive systems where reliability and thermal efficiency are critical.

FAQ

What is the exact float voltage programmed in LT3650IMSE-4.2#TRPBF?

The LT3650IMSE-4.2#TRPBF has a factory-trimmed float voltage of 4.20V ±0.02V, verified across –40°C to 85°C. This value is fixed and non-adjustable - distinct from the LT3650-4.1 variant (4.10V). The 0.5% accuracy ensures compliance with JEITA standards for single-cell Li-Ion charging and maximizes cycle life without overvoltage risk.

Does LT3650IMSE-4.2#TRPBF require an external blocking diode on the VIN line?

No, the LT3650IMSE-4.2#TRPBF integrates reverse-voltage protection and can be connected directly to the input supply without an external blocking diode. This eliminates ~0.3V forward drop loss and associated heat generation, improving efficiency and simplifying layout - confirmed in the Absolute Maximum Ratings and Applications Information sections of the official datasheet.

How does the CLP pin function in LT3650IMSE-4.2#TRPBF, and what is its design impact?

The CLP pin in LT3650IMSE-4.2#TRPBF monitors total input current and dynamically reduces battery charge current to preserve power for system loads. When V_CLP–VIN reaches 50mV, the IC throttles I_CHG to maintain that threshold - enabling priority allocation of input power between battery and MCU/peripherals. If unused, CLP must be tied to VIN.

Can LT3650IMSE-4.2#TRPBF operate with input voltages below 7.5V?

The LT3650IMSE-4.2#TRPBF requires ≥7.5V on VIN for initial start-up, but can sustain operation down to 4.75V once running - provided the BOOST–SW voltage remains >2V. This behavior is enabled by the bootstrap capacitor recharge path; operation below 7.5V is only valid after startup and must be validated per application conditions.

What is the thermal pad (Pin 13) connection requirement for LT3650IMSE-4.2#TRPBF?

The exposed thermal pad (Pin 13, SGND) of the LT3650IMSE-4.2#TRPBF must be soldered to a dedicated PCB copper pour connected to system ground. This is mandatory for thermal performance - θ_JA = 43°C/W assumes full pad soldering. Omitting this connection risks junction temperature exceeding 125°C under 2A continuous charge, triggering thermal foldback or shutdown.