Analog Devices Inc. LTC1729CS8-4.1#TRPBF

Overview

LTC1729CS8-4.1#TRPBF from Analog Devices (formerly Linear Technology) is a precision lithium-ion battery charge termination controller for single-cell 4.1V systems. It provides C/10 current detection, 3-hour time-out termination, trickle-charge preconditioning below 2.7V/cell, temperature qualification via NTC thermistor input, and automatic battery/charger presence detection. It interfaces with external step-down or SEPIC chargers such as LT1510 or LT1769 in portable power management circuits.

For engineers reviewing the LTC1729CS8-4.1#TRPBF datasheet, LTC1729CS8-4.1#TRPBF pinout, LTC1729CS8-4.1#TRPBF application, or LTC1729CS8-4.1#TRPBF equivalent, key selection criteria include its ±0.2% internal voltage feedback divider accuracy, 0°C to 70°C operating range, 8-pin SO package compatibility, and explicit support for 4.1V/cell termination - distinct from 4.2V/8.2V/8.4V variants.

Technical Context

The LTC1729CS8-4.1#TRPBF implements a state-machine-based control architecture with six internal comparators (COMP1–COMP6), a 131kHz trimmed oscillator, and digital timers for preconditioning (1 hr), main charging (3 hr), and filtering (0.859 sec VMAX, 3.5 sec VC/10). Its logic block enforces strict sequencing: trickle charge → full charge → C/10 detection or timeout → Done/No Bat transitions.

It integrates precision analog monitoring: OVP pin references a trimmed 2.465V threshold for 4.1V/cell operation (±0.2%); NTC pin uses 100µA bias to interpret 10kΩ thermistor voltages (0.206V reset, 0.405V hot hold, 2.79V cold hold); SENSE pin sinks 100µA to set C/10 threshold via external resistor; BAT pin sources 12mA (trickle) or 1.3mA (charge) with 4.5V/cell clamp.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (narrow, 0.150"), JEDEC MS-012, body size 4.90mm × 3.90mm × 1.75mm, lead pitch 1.27mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar lithium-ion charge termination applications.

Compared with LTC1729CS8-4.1#TRPBF, the 4.2V variant changes only the internal reference for higher cell voltage compliance, while the MSOP version retains identical behavior in a smaller package - neither offers pin-to-pin compatibility with non-LTC1729 family members.

Availability

LTC1729CS8-4.1#TRPBF is available at Aetrix Electronics and suitable for cellular phone charging, PDA power management, and cradle charger systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LTC1729CS8-4.1#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 and maintains full technical and manufacturing continuity for the LTC product line, including precision analog ICs for power management.

The LTC1729 series was designed specifically for smart lithium-ion battery termination in portable consumer electronics, integrating safety-critical functions like thermal qualification, overvoltage clamp, and programmable time/current cutoff into a minimal-footprint controller.

FAQ

What is the exact termination voltage supported by LTC1729CS8-4.1#TRPBF?

LTC1729CS8-4.1#TRPBF is factory-trimmed for 4.1V/cell operation, with an internal 2.465V reference at the OVP pin and ±0.2% accuracy. This corresponds to a precise 4.100V ±8.2mV battery voltage threshold under full operating conditions, confirmed in the Electrical Characteristics table on page 2 of the datasheet.

Does LTC1729CS8-4.1#TRPBF support two-cell battery configurations?

No - LTC1729CS8-4.1#TRPBF is strictly a single-cell 4.1V termination controller. Two-cell applications require LTC1729CS8-8.2#TRPBF (8.2V) or LTC1729CS8-8.4#TRPBF (8.4V), which share identical pinout and logic but use different internal reference dividers calibrated for 2× cell voltage.

How does the NTC thermistor interface work on LTC1729CS8-4.1#TRPBF?

LTC1729CS8-4.1#TRPBF supplies 100µA through the NTC pin to bias a 10kΩ NTC thermistor. Voltage thresholds - 0.206V (reset), 0.405V (hot hold), and 2.79V (cold hold) - correspond to 0°C and 50°C boundaries. The pin must never be left floating; a 10kΩ resistor is required if thermal qualification is disabled.

Can LTC1729CS8-4.1#TRPBF be used with chargers other than Linear/Analog Devices parts?

Yes - LTC1729CS8-4.1#TRPBF interfaces with any constant-voltage/constant-current charger that accepts an open-drain enable signal on VC and provides a compatible SENSE node. Its six-pin integration (VC, STATUS, BAT, SENSE, NTC, OVP) is agnostic to charger topology, including third-party buck or SEPIC controllers meeting voltage/current drive specs.

What happens to LTC1729CS8-4.1#TRPBF when the wall adapter is disconnected?

When V_CC drops below ~6V UVLO threshold, LTC1729CS8-4.1#TRPBF enters high-impedance shutdown: VC and STATUS go high-Z, BAT and SENSE current sources disable, and the OVP divider disconnects from the battery. This minimizes parasitic drain - critical for maintaining battery charge during adapter-off periods.