Analog Devices Inc. LTC1731ES8-8.2#TRPBF

Overview

LTC1731ES8-8.2#TRPBF from Analog Devices (formerly Linear Technology) is a complete constant-current/constant-voltage linear charger controller for 2-cell lithium-ion batteries, delivering 8.2V regulated float voltage with ±1% accuracy, programmable charge current up to 500mA via external R_PROG/R_SENSE, and automatic C/10 end-of-charge detection. It enables compact, low-quiescent charging in handheld computers and cellular phones.

For engineers reviewing the LTC1731ES8-8.2#TRPBF datasheet, LTC1731ES8-8.2#TRPBF pinout, LTC1731ES8-8.2#TRPBF application, or LTC1731ES8-8.2#TRPBF equivalent, key selection considerations include its 8.2V fixed float voltage, 15µA sleep-mode battery drain, MSOP-8/SO-8 package compatibility, and support for external P-channel MOSFET or high-gain PNP pass devices.

Technical Context

The LTC1731ES8-8.2#TRPBF implements dual-loop control: a current amplifier servoing the DRV pin to maintain precise IBAT via R_SENSE, and a voltage amplifier regulating BAT to 8.2V using an internal 2.457V reference and precision resistor divider. Its architecture supports both full CC/CV charging and constant-current-only mode when TIMER is tied to VCC.

Charge termination combines hardware-based C/10 detection (with 320ms debounce) and a programmable timer set by CTIMER (3 hours per 0.1µF), while undervoltage lockout (8.2V threshold with 200mV hysteresis) and automatic trickle charge (10% IBAT below 4.95V BAT) ensure safe startup and fault handling.

Key Specifications

Pinout & Package

Package: 8-pin SO (Small Outline, narrow 0.150"), RoHS-compliant, surface-mount. Pin pitch: 1.27mm, body size: 4.9mm × 3.9mm × 1.75mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar linear battery charger controller applications.

Compared with LTC1731ES8-8.2#TRPBF, the LTC1731ES8-8.4#TRPBF offers identical functionality with only float voltage shifted for different cell chemistry, whereas the LTC1732ES8#TRPBF adds system-level intelligence at the cost of increased BOM count and non-interchangeable pin mapping.

Availability

LTC1731ES8-8.2#TRPBF is available at Aetrix Electronics and suitable for cellular phones, handheld computers, and charging docks requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for LTC1731ES8-8.2#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 product support, documentation, and manufacturing continuity for all Linear-branded ICs.

The LTC1731 family was designed specifically for space-constrained, low-noise linear charging of multi-cell Li-Ion batteries in portable consumer and industrial equipment where simplicity, reliability, and minimal external components are critical.

FAQ

What is the exact float voltage tolerance of the LTC1731ES8-8.2#TRPBF?

The LTC1731ES8-8.2#TRPBF delivers a nominal 8.2V float voltage with a guaranteed tolerance of ±1% over the full operating temperature range (–40°C to 85°C), corresponding to 8.118V to 8.282V. This specification is achieved using an internal precision 2.457V reference and laser-trimmed resistor divider, ensuring consistent 2-cell Li-Ion termination without external calibration.

Can the LTC1731ES8-8.2#TRPBF charge NiMH batteries?

Yes, the LTC1731ES8-8.2#TRPBF can charge NiMH batteries in constant-current-only mode by connecting the TIMER pin to VCC. In this configuration, the voltage regulation loop and timer are disabled, converting the IC into a programmable current source. External termination (e.g., –ΔV or temperature cutoff) must be implemented, as the built-in C/10 and timer functions are inactive.

What is the minimum input voltage required for the LTC1731ES8-8.2#TRPBF to operate?

The LTC1731ES8-8.2#TRPBF requires a minimum input supply voltage (VCC) of 8.2V to exit undervoltage lockout and begin charging, with full specification compliance from 8.8V to 12V. Below 8.2V, the IC remains in shutdown; hysteresis of 200mV prevents oscillation near the threshold. For 2-cell Li-Ion, this ensures sufficient headroom above the 8.2V float voltage.

How does the LTC1731ES8-8.2#TRPBF handle deeply discharged batteries?

The LTC1731ES8-8.2#TRPBF automatically initiates trickle charge at 10% of the programmed full-scale current when the BAT pin voltage is below 4.95V. This low-current pre-charge continues until the battery reaches 4.95V or one quarter of the total timer duration elapses-whichever occurs first-preventing damage to over-discharged cells while enabling safe recovery.

Is the LTC1731ES8-8.2#TRPBF pin-compatible with the LTC1731EMS8-8.2#TRPBF?

Yes, the LTC1731ES8-8.2#TRPBF (SO-8 package) and LTC1731EMS8-8.2#TRPBF (MSOP-8 package) share identical pinout, electrical specifications, and functional behavior. The only difference is the physical package: SO-8 has 1.27mm pitch and larger footprint; MSOP-8 has 0.65mm pitch and 3mm × 3mm body. Both are RoHS-compliant and support the same PCB layout strategies for signal integrity.