Analog Devices Inc. LTC1734ES6-4.1#TRPBF

Overview

LTC1734ES6-4.1#TRPBF from Analog Devices (formerly Linear Technology) is a single-cell Li-ion linear battery charger controller in TSOT-23-6 package, delivering 4.1V ±1% float voltage, programmable 200–700mA constant current via external resistor, and PROG-pin-based current monitoring for microcontroller-driven charge termination - used in compact portable devices like digital cameras and handheld computers.

For engineers reviewing the LTC1734ES6-4.1#TRPBF datasheet, LTC1734ES6-4.1#TRPBF pinout, LTC1734ES6-4.1#TRPBF application, or LTC1734ES6-4.1#TRPBF equivalent, key selection concerns include 4.1V vs 4.2V preset voltage accuracy, manual shutdown behavior via PROG pin floating, sleep-mode battery drain (<1µA), thermal/overcurrent protection, and compatibility with low-V_CE(sat) PNP pass transistors.

Technical Context

The LTC1734ES6-4.1#TRPBF implements a dual-loop control architecture: A2 amplifier regulates constant-current mode by comparing PROG pin voltage (1.5V reference) against current-sense-derived feedback, while A1 compares a precision-resistor-divided BAT voltage to a 2.5V internal reference to enforce 4.1V constant-voltage regulation. It requires an external PNP pass transistor and uses a 0.06Ω internal sense resistor with 1000:1 current scaling to PROG.

Undervoltage lockout (UVLO) activates below 4.41V (entry) and releases above 4.56V (exit) with 150mV hysteresis; manual shutdown triggers when PROG pin voltage exceeds 2.15V (threshold) due to internal 3µA pull-up; sleep mode engages automatically when VCC = 0V, reducing battery drain to <1µA via reverse-biased PNP B-E junction leakage.

Key Specifications

Pinout & Package

Package: TSOT-23-6 (S6), 6-lead plastic thin small-outline transistor, 1mm maximum height, θ_JA = 230°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP73831T-2DCI/OT and BQ24040DRCR, the LTC1734ES6-4.1#TRPBF uniquely delivers 4.1V precision regulation, external PNP flexibility for high-efficiency low-V_CE(sat) designs, and analog PROG-pin current telemetry - making it irreplaceable in cost-sensitive, height-constrained, or firmware-terminated 4.1V Li-ion systems.

Availability

LTC1734ES6-4.1#TRPBF is available at Aetrix Electronics and suitable for digital cameras, handheld computers, and charging docks requiring stable component supply, long-term manufacturability, and guaranteed lead-free compliance.

Supply support for LTC1734ES6-4.1#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 its high-performance analog IC portfolio, emphasizing precision, power efficiency, and robustness in battery management and signal conditioning.

The LTC1734 product line was designed specifically for low-cost, space-constrained single-cell Li-ion charging applications where external PNP flexibility, analog current monitoring, and selectable 4.1V/4.2V float voltages provide critical design advantages over fully integrated alternatives.

FAQ

What is the exact float voltage tolerance of the LTC1734ES6-4.1#TRPBF?

The LTC1734ES6-4.1#TRPBF guarantees a 4.1V float voltage with ±1% accuracy over the full –40°C to +85°C operating temperature range, meaning the actual regulated voltage falls between 4.059V and 4.141V when IBAT = 10mA and VCC is 4.55–8V. This tight tolerance ensures consistent charge termination across environmental extremes and prevents overvoltage stress on sensitive Li-ion cathodes.

How does the LTC1734ES6-4.1#TRPBF achieve charge current monitoring without a sense resistor?

The LTC1734ES6-4.1#TRPBF uses an internal 0.06Ω current sense resistor in series with the ISENSE pin, scaling the PNP emitter current (IBAT + IB) by 1000:1 to generate a proportional voltage at the PROG pin. With a 1.5V reference, VPROG = 1.5V at full-scale current, and IBAT = 1000 × (VPROG/RPROG). This eliminates external shunts while enabling direct MCU ADC measurement - a core feature of the LTC1734ES6-4.1#TRPBF.

Can the LTC1734ES6-4.1#TRPBF be used with NiMH batteries?

Yes, the LTC1734ES6-4.1#TRPBF can charge NiMH batteries by grounding the BAT pin to disable the 4.1V voltage regulation loop, leaving only the constant-current loop active. The PROG resistor then sets a stable current source (50–700mA), and external voltage or temperature-based termination must be implemented - the LTC1734ES6-4.1#TRPBF itself does not provide NiMH-specific delta-V or dT/dt detection.

What happens to battery drain current when the LTC1734ES6-4.1#TRPBF is in manual shutdown mode?

In manual shutdown mode (PROG pin floated), the LTC1734ES6-4.1#TRPBF draws less than ±1µA from the battery (IBMS), verified over –40°C to +85°C. This negligible drain preserves battery charge during long-term storage or standby - a key advantage over controllers that leak hundreds of microamps in shutdown, especially in always-connected accessories.

Which external PNP transistor parameters are critical for reliable operation of the LTC1734ES6-4.1#TRPBF?

Critical PNP parameters for the LTC1734ES6-4.1#TRPBF include minimum β > 23 (to sustain 700mA with 30mA DRIVE sink), V_CE(sat) < 0.5V at rated current (to avoid excessive base drive and thermal runaway), and power dissipation rating sufficient for PD = IBAT × (VCC_MAX – VBAT_MIN). Devices like FMMT549 or FCX589 are validated in Linear's reference designs for the LTC1734ES6-4.1#TRPBF.