Analog Devices Inc. LTC1732EMS-4.2#TRPBF

Overview

LTC1732EMS-4.2#TRPBF from Analog Devices (formerly Linear Technology) is a precision linear battery charger controller for single-cell 4.2V lithium-ion batteries. It delivers constant-current/constant-voltage charging with 1% float voltage accuracy, programmable charge current (e.g., 500 mA ±7%), and automatic trickle-charge initiation below 2.457 V. It is used in portable medical devices requiring low quiescent battery drain and reliable end-of-charge detection.

For engineers reviewing the LTC1732EMS-4.2#TRPBF datasheet, LTC1732EMS-4.2#TRPBF pinout, LTC1732EMS-4.2#TRPBF application, or LTC1732EMS-4.2#TRPBF equivalent, key selection criteria include its 4.05 V recharge threshold, C/10 end-of-charge detection output, 7 µA sleep-mode battery drain, MSOP-10 package compatibility, and SEL-pin–forced 4.2 V float voltage configuration.

Technical Context

The LTC1732EMS-4.2#TRPBF implements a dual-loop analog control architecture: a current amplifier servoing an external P-channel MOSFET gate to regulate charge current via RSENSE and RPROG, and a voltage amplifier with internal 2.457 V reference and precision resistor divider to regulate BAT pin voltage to 4.2 V ±1%. Its C/10 comparator monitors current decay independently of timer expiration.

It features integrated undervoltage lockout (4.1 V threshold with 200 mV hysteresis), automatic sleep mode when VCC drops within 54 mV of VBAT, and a dedicated ACPR open-drain output that sinks 5 mA to indicate wall adapter presence. The TIMER pin supports three modes: timed termination (via CTIMER), constant-current-only operation (TIER = VCC), or timer disable (TIMER = GND).

Key Specifications

Pinout & Package

Package: 10-lead MSOP (MS10), 3.0 mm × 3.0 mm × 1.1 mm, exposed pad optional, RoHS-compliant, rated for –40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar lithium-ion linear charger controller applications.

Compared with LTC1732EMS-4.2#TRPBF, LTC4054-4.2 reduces external component count but removes critical diagnostics (C/10, ACPR, TIMER), while MAX1555 sacrifices programmability and deep-charge capability for integration and USB simplicity-neither offers the same combination of precision, configurability, and industrial-grade robustness.

Availability

LTC1732EMS-4.2#TRPBF is available at Aetrix Electronics and suitable for portable medical monitors, handheld diagnostic scanners, wearable health trackers, industrial handheld terminals, and battery-backed data loggers requiring stable component supply across multi-year production cycles.

Supply support for LTC1732EMS-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 and maintains full technical support, manufacturing continuity, and long-term product roadmaps for legacy Linear parts including the LTC series.

The LTC1732EMS-4.2#TRPBF belongs to Linear's precision analog power management portfolio, designed specifically for space-constrained, safety-critical Li-Ion charging applications demanding high voltage accuracy, low quiescent drain, and robust fault handling.

FAQ

What is the exact float voltage setpoint of the LTC1732EMS-4.2#TRPBF?

The LTC1732EMS-4.2#TRPBF is factory-configured to deliver a precise 4.2 V float voltage at the BAT pin, with guaranteed accuracy of ±1% (4.158 V to 4.242 V) over the full –40°C to +85°C operating temperature range. This value is fixed by internal laser-trimmed resistors and requires no external adjustment-SEL pin must be connected to VCC to activate this 4.2 V mode.

How does the LTC1732EMS-4.2#TRPBF detect end-of-charge?

The LTC1732EMS-4.2#TRPBF uses dual independent methods: (1) the C/10 comparator detects when charge current falls to ≤10% of the programmed value (e.g., ≤50 mA for 500 mA setting), pulling CHRG to high-impedance after a 15 ms debounce; and (2) the TIMER pin capacitor sets total charge duration. Both signals are available simultaneously for redundant safety monitoring in certified medical devices.

Can the LTC1732EMS-4.2#TRPBF be used with 4.1 V lithium-ion cells?

No-the LTC1732EMS-4.2#TRPBF is specifically calibrated for 4.2 V cells and has a fixed 4.05 V recharge threshold. Using it with 4.1 V cells risks overcharging due to mismatched voltage setpoints and incorrect recharge behavior. For 4.1 V cells, the LTC1732EMS-4 variant (with SEL = GND) must be selected instead.

What is the minimum input voltage required for the LTC1732EMS-4.2#TRPBF to begin charging?

The LTC1732EMS-4.2#TRPBF requires VCC ≥ 4.5 V to operate normally, with undervoltage lockout releasing at 4.1 V (typical) and 4.5 V (max). However, charging only commences when both VCC exceeds UVLO and the voltage difference VCC – VBAT exceeds 54 mV-ensuring sufficient headroom for the external P-channel MOSFET to remain fully enhanced during regulation.

Does the LTC1732EMS-4.2#TRPBF support automatic battery insertion detection?

Yes-the LTC1732EMS-4.2#TRPBF automatically initiates a new charge cycle when a discharged battery is connected while input power is applied. If the battery voltage is below 4.05 V, the device starts trickle charge immediately; if above, it enters fast-charge mode. This behavior is intrinsic to the analog control loop and requires no firmware intervention or external circuitry.