Analog Devices Inc. LT3650IMSE-4.1#TRPBF

Overview

LT3650IMSE-4.1#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, 4.1V float voltage, and integrated 2A switch. It delivers constant-current/constant-voltage charging with programmable C/10 or timer-based termination, preconditioning for deeply discharged batteries, and NTC temperature monitoring - used in 12V–24V automotive cradle chargers and industrial handheld instruments.

For engineers reviewing the LT3650IMSE-4.1#TRPBF datasheet, LT3650IMSE-4.1#TRPBF pinout, LT3650IMSE-4.1#TRPBF application, or LT3650IMSE-4.1#TRPBF equivalent, key selection considerations include its 4.1V fixed float voltage, MSOP-12 package with exposed thermal pad, 0.5% float voltage accuracy, 5% charge current accuracy, and compatibility with high-input-voltage battery systems requiring robust bad-battery detection and auto-recharge.

Technical Context

The LT3650IMSE-4.1#TRPBF employs average current mode control at 1MHz fixed frequency, using an internal 2A switch driven by a bootstrapped BOOST rail to achieve high efficiency without external blocking diodes. Its VIN-to-SW switching architecture supports direct connection to unregulated 12V/24V rails while maintaining precise current regulation via SENSE–BAT differential sensing.

It integrates dual termination logic: C/10 detection (triggered at 10mV sense threshold) and a user-programmable safety timer (3-hour default via 0.68µF capacitor on TIMER pin), with automatic preconditioning below 2.9V BAT and auto-restart at 97.5% of 4.1V float voltage. The IC also provides binary-coded open-collector status outputs (CHRG/FAULT) and NTC-based thermal fault management with 0.29V–1.36V active window.

Key Specifications

Pinout & Package

LT3650IMSE-4.1#TRPBF is housed in a 12-lead plastic MSOP package (3mm × 4.9mm) with exposed thermal pad (Pin 13 = GND), 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 charger applications.

Compared with LT3650IMSE-4.1#TRPBF, LT3652IMSE-4.1#TRPBF offers enhanced input ruggedness but same thermal and footprint behavior, while BQ24610RGER trades integration for design flexibility - making LT3650IMSE-4.1#TRPBF optimal for cost-sensitive, space-constrained 2A monolithic charger implementations.

Availability

LT3650IMSE-4.1#TRPBF is available at Aetrix Electronics and suitable for automotive cradle chargers, industrial handheld instruments, desktop docking stations, and notebook auxiliary charging systems requiring stable component supply and long-term production continuity.

Supply support for LT3650IMSE-4.1#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LT3650 product line delivers monolithic, high-input-voltage Li-Ion chargers for harsh-environment applications where reliability, thermal efficiency, and minimal external components are critical - targeting 12V–24V battery-powered equipment.

FAQ

What is the exact float voltage of the LT3650IMSE-4.1#TRPBF?

The LT3650IMSE-4.1#TRPBF has a factory-trimmed float voltage of 4.10 V with ±0.02 V (±0.5%) accuracy over temperature. This value is fixed and non-adjustable - distinct from the LT3650-4.2 variant (4.20 V). The specification applies across the full –40°C to 85°C operating range and ensures precise termination for single-cell Li-Ion batteries without external feedback resistors.

Does the LT3650IMSE-4.1#TRPBF require an external blocking diode on the VIN line?

No, the LT3650IMSE-4.1#TRPBF does not require an external blocking diode on VIN. Its internal architecture provides reverse-voltage protection, allowing direct connection to unregulated 12V or 24V sources. This eliminates power loss and board space associated with discrete diodes - confirmed in the "Operation" section and Absolute Maximum Ratings table of the official datasheet.

How is charge current programmed on the LT3650IMSE-4.1#TRPBF?

Charge current is set by the external sense resistor (RSENSE) between SENSE and BAT pins: RSENSE = 0.1 V / ICHG(MAX). For example, 0.05 Ω yields 2 A maximum. The RNG/SS pin further enables dynamic adjustment or soft-start via a resistor (50 µA sourced) or capacitor, but the base current limit is defined solely by RSENSE and the 100 mV full-scale sense threshold.

What happens if the battery voltage is below 2.9V when the LT3650IMSE-4.1#TRPBF starts?

If BAT voltage is below 2.9V at startup, the LT3650IMSE-4.1#TRPBF automatically enters precondition mode, reducing charge current to 15% of the programmed maximum (e.g., 300 mA for 2 A setting) until BAT rises above 2.9V. If the battery fails to respond within 22.5 minutes (1/8 of 3-hour timer), a bad-battery fault is asserted, pulling FAULT low and halting charging.

Can the LT3650IMSE-4.1#TRPBF be used with a thermistor other than 10kΩ B=3380?

The LT3650IMSE-4.1#TRPBF is characterized for use with a 10 kΩ, B=3380 NTC thermistor, which produces the specified 0.29 V–1.36 V voltage range at 0°C–40°C. While alternative thermistors may function, the NTC thresholds and hysteresis are fixed in silicon - deviation from the recommended part risks inaccurate temperature detection or premature fault triggering. No calibration or adjustment capability exists on the IC.