Analog Devices Inc. LT3650EMSE-4.2#PBF

Overview

LT3650EMSE-4.2#PBF 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 programmable C/10 or timer-based termination. It integrates a 2A internal switch, NTC temperature monitoring, bad-battery detection, and auto-recharge at 97.5% float voltage - used in 12V–24V automotive cradle chargers and industrial handheld instruments.

For engineers reviewing the LT3650EMSE-4.2#PBF datasheet, LT3650EMSE-4.2#PBF pinout, LT3650EMSE-4.2#PBF application, or LT3650EMSE-4.2#PBF equivalent, key selection criteria include its 4.2V fixed float voltage, MSOP-12 package with exposed thermal pad, 1MHz average current mode control, ±0.5% float voltage accuracy, and support for system current limiting via CLP pin.

Technical Context

The LT3650EMSE-4.2#PBF implements a fixed-frequency (1MHz) average current mode buck regulator architecture with integrated 2A power switch and bootstrapped gate drive (BOOST pin). Its control loop directly regulates average inductor current using SENSE–BAT differential voltage feedback and servo-controlled ITH voltage.

It supports dual termination modes: C/10 detection (10mV sense threshold) or internal timer (3-hour default via 0.68µF capacitor on TIMER pin), with preconditioning below 2.9V BAT and auto-restart at 97.5% float voltage. NTC monitoring uses 50µA bias and 0.29V–1.36V valid range for 0°C–40°C operation.

Key Specifications

Pinout & Package

LT3650EMSE-4.2#PBF is housed in a 12-lead plastic MSOP package (3mm × 4.9mm) with exposed thermal pad (Pin 13 = SGND), optimized for thermal performance in space-constrained battery charging applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC4000-4.2#PBF, LT3650EMSE-4.2#PBF offers lower BOM count and smaller footprint due to integrated 2A switch, while BQ24610RGER trades away critical safety features (NTC, bad-battery detection) for marginal current increase - making LT3650EMSE-4.2#PBF optimal for space- and safety-constrained industrial designs.

Availability

LT3650EMSE-4.2#PBF is available at Aetrix Electronics and suitable for 12V–24V automotive cradle chargers, industrial handheld instruments, desktop cradle chargers, and auxiliary notebook computer charging systems requiring stable component supply and long-term manufacturability.

Supply support for LT3650EMSE-4.2#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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and power management ICs for precision, reliability, and efficiency-critical applications.

The LT3650EMSE-4.2#PBF belongs to ADI's Linear Technology battery charger product line, engineered for high-input-voltage, single-cell Li-Ion charging in automotive, industrial, and portable equipment where integration, thermal safety, and wide VIN range are essential.

FAQ

What is the exact float voltage of the LT3650EMSE-4.2#PBF?

The LT3650EMSE-4.2#PBF has a fixed nominal float voltage of 4.20V, specified as 4.18V to 4.22V (typical 4.20V) over temperature and line conditions. This value is factory-trimmed and guaranteed within ±0.5% accuracy, matching standard single-cell Li-Ion battery requirements. The "-4.2" suffix explicitly denotes this 4.2V variant, distinguishing it from the LT3650-4.1 version with 4.1V float.

Does the LT3650EMSE-4.2#PBF support NTC-based temperature monitoring?

Yes, the LT3650EMSE-4.2#PBF supports NTC thermistor monitoring via Pin 8 (NTC), which sources a precise 50µA bias current. When paired with a 10kΩ, B=3380 NTC, it detects temperatures outside 0°C–40°C (voltage <0.29V or >1.36V), disables charging, and pulls both CHRG and FAULT low. Hysteresis is ~5°C per threshold, and the function remains active as long as thermistor resistance stays below 250kΩ.

How is charge termination configured on the LT3650EMSE-4.2#PBF?

Charge termination on the LT3650EMSE-4.2#PBF is selected via the TIMER pin (Pin 6): connect a capacitor to GND for timer-based termination (e.g., 0.68µF = 3 hours), or tie TIMER directly to GND for C/10-only termination. With timer enabled, charging continues beyond C/10 to top off the battery; with timer disabled, termination occurs strictly when sensed current falls to I_MAX/10 (10mV across R_SENSE).

What package type and thermal characteristics does the LT3650EMSE-4.2#PBF use?

The LT3650EMSE-4.2#PBF uses a 12-lead plastic MSOP package (3mm × 4.9mm) with exposed thermal pad (Pin 13 = SGND). Its thermal resistance is θ_JA = 43°C/W and θ_JC = 3°C/W. The exposed pad must be soldered to PCB ground for effective heat dissipation - critical for sustaining 2A continuous operation in ambient temperatures up to 85°C.

Can the LT3650EMSE-4.2#PBF operate with input voltages below 7.5V?

No - the LT3650EMSE-4.2#PBF requires either VIN ≥ 7.5V or (V_BOOST – V_SW) > 2V to start up. Below 7.5V, the IC remains in UVLO state unless the BOOST–SW differential exceeds 2V, which typically occurs only after initial switching begins. Its operational input range is 4.75V–32V, but startup is gated by this dual-condition requirement to ensure reliable bootstrap capacitor charging.