Analog Devices Inc. LTC1729CS8-4.1#PBF

Overview

LTC1729CS8-4.1#PBF from Analog Devices (formerly Linear Technology) is a lithium-ion battery charge termination controller for 1-cell systems with precise 4.1V/cell voltage regulation, built-in 3-hour time-out, C/10 current detection, and temperature qualification via NTC thermistor monitoring. It interfaces with external step-down or SEPIC chargers (e.g., LT1510, LT1769) to manage full-charge cutoff, trickle preconditioning below 2.7V/cell, and safe thermal window enforcement (0°C–50°C). Used in compact portable electronics requiring reliable, low-footprint charge control.

For engineers reviewing the LTC1729CS8-4.1#PBF datasheet, LTC1729CS8-4.1#PBF pinout, LTC1729CS8-4.1#PBF application, or LTC1729CS8-4.1#PBF equivalent, key selection criteria include its ±0.2% internal voltage feedback divider accuracy, 8-pin SO package compatibility, NTC-based thermal hold/reset behavior, and explicit support for 4.1V/cell (not 4.2V) termination thresholds per device marking and electrical specs.

Technical Context

The LTC1729CS8-4.1#PBF implements a state-machine-driven charge controller with six internal comparators, UVLO (6.0V typ), and a 131kHz trimmed oscillator driving 25-bit counter logic. Its OVP pin references an internal precision 0.2% resistor divider set for 4.1V/cell - yielding VOVP = 2.465V (typ) - while VMAX and VMIN thresholds are calibrated to 4.51V and 2.70V (high-going) respectively for 4.1V variants.

It provides three distinct operational states: Precondition (12mA trickle charge, 1-hour timeout), Charger "ON" (1.3mA BAT drive, 3-hour timeout), and Hold/Reset modes triggered by NTC voltage excursions (<0.2V reset, <0.405V or >2.79V hold). The STATUS and VC pins operate as open-drain outputs with defined VOL (0.9V max @ 3mA) and soft-pull-down (50µA) behavior during C/10 detection.

Key Specifications

Pinout & Package

Package: 8-lead plastic small-outline (narrow, 0.150") SO package (S8), JEDEC MS-012AC compliant, 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 LTC1729CS8-4.2#PBF, the LTC1729CS8-4.1#PBF delivers tighter voltage regulation (0.2% vs same die but different trim) for chemistries requiring 4.1V/cell, while BQ29700DSET offers programmability at the expense of absolute accuracy and integrated thermal bias - making LTC1729CS8-4.1#PBF optimal for precision-critical, fixed-voltage legacy systems.

Availability

LTC1729CS8-4.1#PBF is available at Aetrix Electronics and suitable for cellular phones, PDAs, cradle chargers, and camcorders requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing for production builds.

Supply support for LTC1729CS8-4.1#PBF 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 support for legacy Linear ICs including the LTC1729 series. Linear pioneered high-precision analog ICs for power management and signal conditioning.

The LTC1729 series was designed specifically for smart lithium-ion battery charge termination in space-constrained portable electronics, integrating voltage monitoring, thermal qualification, and dual-criteria (time + current) cutoff in a minimal 8-pin footprint.

FAQ

What is the exact voltage threshold for overvoltage protection in the LTC1729CS8-4.1#PBF?

The LTC1729CS8-4.1#PBF uses an internal precision resistor divider trimmed to deliver 2.465V (typ) at the OVP pin when VBAT = 4.1V/cell. This corresponds to a high-going VMAX threshold of 4.51V/cell (min 4.25V, max 4.75V) - verified in the Electrical Characteristics table for LTC1729-4.1 variants. The value is factory-calibrated and not user-adjustable.

Does the LTC1729CS8-4.1#PBF support 2-cell battery configurations?

No - the LTC1729CS8-4.1#PBF is explicitly rated for 1-cell operation at 4.1V/cell. While the LTC1729 family includes 8.2V/8.4V variants (e.g., LTC1729CS8-8.2#PBF) for 2-cell stacks, the -4.1 suffix and associated electrical specs (VOVP, VMAX, VMIN) confirm single-cell use only. Using it for 2-cell would result in premature termination or failure to regulate.

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

The LTC1729CS8-4.1#PBF sources 100µA from the NTC pin to bias a 10kΩ NTC thermistor. Voltage thresholds are fixed: cold hold activates above 2.79V (≈0°C), hot hold below 0.405V (≈50°C), and reset below 0.206V. Leaving the pin unconnected is prohibited; a 10kΩ resistor must substitute if thermal qualification is disabled.

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

Yes - the LTC1729CS8-4.1#PBF interfaces with any external charger that accepts an open-drain enable signal (VC pin) and provides a current-sense node compatible with the SENSE pin's 100µA sink. Its six-pin integration method (OVP, BAT, SENSE, VC, STATUS, NTC) is generic, though timing and voltage thresholds must align with the host charger's capabilities.

What is the function of the STATUS pin during C/10 detection in the LTC1729CS8-4.1#PBF?

During C/10 detection, the LTC1729CS8-4.1#PBF disables the hard pull-down MOSFET on the STATUS pin after the charge current remains below C/10 for ≥3 seconds, leaving only a 50µA soft pull-down active. This allows external circuitry (e.g., microcontroller with dual pull-ups) to distinguish three states: charging (low), C/10 reached (mid-level), and timeout complete (high-Z).