Analog Devices Inc. LTC1731ES8-4.2#TRPBF

Overview

LTC1731ES8-4.2#TRPBF from Analog Devices (formerly Linear Technology) is a single-cell lithium-ion linear battery charger controller with 4.2V fixed float voltage, ±1% output voltage accuracy, 5% charge current accuracy via external sense resistor, and integrated C/10 end-of-charge detection for portable electronics power management.

For engineers reviewing the LTC1731ES8-4.2#TRPBF datasheet, LTC1731ES8-4.2#TRPBF pinout, LTC1731ES8-4.2#TRPBF application, or LTC1731ES8-4.2#TRPBF equivalent, key selection criteria include programmable constant-current/constant-voltage operation, 7µA sleep-mode battery drain, MSOP-8/SO-8 package compatibility, and external P-channel MOSFET drive capability.

Technical Context

The LTC1731ES8-4.2#TRPBF implements a precision linear charging architecture using an internal 2.457V reference, trimmed 800Ω resistor, and current amplifier to servo an external P-channel MOSFET gate via the DRV pin. It supports dual-mode operation: constant-current/constant-voltage (CC/CV) for Li-ion with ±1% float voltage regulation, and constant-current-only mode when TIMER pin is tied to VCC.

Charge termination is implemented via dual independent mechanisms: C/10 current detection (with 320ms latch delay) and programmable timer (set by CTIMER capacitor, tTIMER = 3h × CTIMER/0.1µF). Trickle charge activates below 2.457V BAT, delivering 10% of programmed current until threshold is exceeded.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (Small Outline, narrow 0.150") - RoHS-compliant, surface-mount, footprint compatible with industry-standard SOIC-8 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC1731EMS8-4.2, the LTC1731ES8-4.2#TRPBF offers identical electrical performance in SO-8 packaging for legacy footprint compatibility, while the BQ24032ARGTR trades external component count for reduced configurability in Li-ion charging control.

Availability

LTC1731ES8-4.2#TRPBF is available at Aetrix Electronics and suitable for smartphone charging circuits, handheld medical devices, USB-C docking stations, and industrial handheld scanners requiring stable component supply and long-term production continuity.

Supply support for LTC1731ES8-4.2#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, Inc. (acquired Linear Technology in 2017) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and power management ICs for precision instrumentation, industrial, automotive, and communications markets.

The LTC1731 product line delivers highly accurate, standalone linear battery charger controllers optimized for single-cell Li-ion systems where simplicity, reliability, and minimal external components are critical design goals.

FAQ

What is the exact float voltage setting for the LTC1731ES8-4.2#TRPBF?

The LTC1731ES8-4.2#TRPBF has a factory-trimmed internal float voltage of 4.2V with ±1% accuracy over the full operating temperature range (−40°C to 85°C). This value is fixed and non-adjustable, distinguishing it from the LTC1731-4.1 variant (4.1V). The specification is guaranteed under conditions where VCC is between 5V and 12V, and applies to both SO-8 and MSOP-8 package variants of the LTC1731ES8-4.2#TRPBF.

How does the LTC1731ES8-4.2#TRPBF implement charge termination?

The LTC1731ES8-4.2#TRPBF uses two independent termination methods: C/10 current detection and a programmable timer. When battery current drops to ≤10% of the programmed full-scale value, an internal comparator triggers after a 320ms latch delay, pulling CHRG high via a 100µA current source. Simultaneously, an external capacitor on the TIMER pin sets total charge time (tTIMER = 3h × CTIMER/0.1µF); expiration forces CHRG into high-impedance state. Either condition halts charging.

Can the LTC1731ES8-4.2#TRPBF be used for NiMH battery charging?

Yes, the LTC1731ES8-4.2#TRPBF can charge NiMH batteries by configuring it in constant-current-only mode: tie the TIMER pin to VCC to disable constant-voltage regulation and internal timer. In this mode, the IC functions as a precision current source with programmable IBAT, but external termination (e.g., −ΔV, temperature cutoff, or timer) is required since C/10 detection and trickle charge are disabled. The LTC1731ES8-4.2#TRPBF retains its 5% current accuracy and 7µA sleep drain in this configuration.

What is the purpose of the PROG pin on the LTC1731ES8-4.2#TRPBF?

The PROG pin on the LTC1731ES8-4.2#TRPBF serves two critical functions: charge current programming and shutdown control. Connecting RPROG from PROG to GND sets IBAT = (2.457V × 800Ω)/(RPROG × RSENSE). Floating the PROG pin activates internal 2.5µA pull-up, raising voltage above 2.457V shutdown threshold and reducing ICC to ~1mA. This provides hardware-level enable/disable without additional logic, making the LTC1731ES8-4.2#TRPBF suitable for simple on/off battery charging control.

Does the LTC1731ES8-4.2#TRPBF require external compensation components?

No, the LTC1731ES8-4.2#TRPBF is internally compensated and stable without external components when driving a P-channel MOSFET. A 10µF capacitor at the BAT pin is recommended to suppress ripple when the battery is disconnected. If using a PNP transistor instead of a MOSFET, a 1000pF capacitor from DRV to VCC is required for loop stability, plus the same 10µF BAT bypass. These capacitors address specific pass device dynamics-not inherent instability of the LTC1731ES8-4.2#TRPBF core.