Analog Devices Inc. LTC1734ES6-4.2#TRPBF

Overview

LTC1734ES6-4.2#TRPBF from Analog Devices (formerly Linear Technology) is a single-cell Li-ion linear battery charger controller in TSOT-23-6 package, delivering 4.2V ±1% constant-voltage regulation and programmable 200–700mA constant-current charging via external R_PROG. It integrates PROG-pin current monitoring, manual shutdown, automatic sleep mode on V_CC removal, and thermal/overcurrent protection-designed for compact portable power management in handheld devices.

For engineers reviewing the LTC1734ES6-4.2#TRPBF datasheet, LTC1734ES6-4.2#TRPBF pinout, LTC1734ES6-4.2#TRPBF application, or LTC1734ES6-4.2#TRPBF equivalent, key selection considerations include its 4.2V float voltage accuracy, 1000× current-sense scaling on PROG, no external blocking diode requirement, 670–1150µA quiescent supply current, and compatibility with low-beta PNP pass transistors (β > 23).

Technical Context

The LTC1734ES6-4.2#TRPBF implements a dual-loop control architecture: A2 amplifier regulates constant-current mode by comparing PROG-pin voltage (1.5V reference) against I_PROG × R_PROG, while A1 compares a precision 2.5V internal reference to a 2.5V divided-down BAT voltage to enforce 4.2V constant-voltage regulation. Its DRIVE pin provides thermally limited base-drive sink current (≥30mA) for an external PNP transistor.

Operation requires no sense resistor or blocking diode; charge current is derived from emitter current through the internal 0.06Ω sense resistor, scaled 1000:1 to PROG. Manual shutdown is triggered when PROG voltage exceeds 2.15V (hysteresis = 90mV), and sleep mode activates when V_CC drops below UVLO entry threshold (4.30–4.53V), reducing battery drain to <1µA.

Key Specifications

Pinout & Package

Package: 6-Lead Plastic TSOT-23 (S6), 1mm profile, RoHS-compliant, tape-and-reel delivery.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP73831T-2DCI/OT and BQ24075RGTR, the LTC1734ES6-4.2#TRPBF offers superior analog current monitoring via PROG pin, wider programmable current range (200–700mA), and lower quiescent current-but requires external PNP transistor and resistor programming, increasing component count while retaining design flexibility.

Availability

LTC1734ES6-4.2#TRPBF is available at Aetrix Electronics and suitable for cellular telephones, handheld computers, and digital cameras requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LTC1734ES6-4.2#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 acquired Linear Technology in 2017 and maintains its high-performance analog IC portfolio, emphasizing precision, reliability, and application-specific integration for power management and signal conditioning.

The LTC1734ES6-4.2#TRPBF belongs to Linear's legacy battery management product line, designed specifically for cost-sensitive, space-constrained portable electronics needing simple, robust, and accurate single-cell Li-ion charging without digital overhead.

FAQ

What is the exact float voltage tolerance of the LTC1734ES6-4.2#TRPBF?

The LTC1734ES6-4.2#TRPBF guarantees a 4.2V float voltage with ±1% accuracy over –40°C to +85°C ambient temperature, corresponding to 4.158V minimum and 4.242V maximum under specified test conditions (I_BAT = 10mA, 4.55V ≤ V_CC ≤ 8V). This tight tolerance ensures compliance with Li-ion cell manufacturer specifications and prevents overcharging-induced degradation.

How does the PROG pin function in both programming and monitoring modes for the LTC1734ES6-4.2#TRPBF?

The PROG pin of the LTC1734ES6-4.2#TRPBF serves dual roles: as a 1.5V virtual ground for setting charge current via R_PROG (I_BAT ≈ 1500/R_PROG), and as an analog monitor output where V_PROG = I_BAT/1000 × R_PROG. This allows direct ADC measurement of real-time charge current without additional components-enabling smart termination decisions in systems using the LTC1734ES6-4.2#TRPBF.

Can the LTC1734ES6-4.2#TRPBF be used to charge NiMH batteries, and if so, how?

Yes, the LTC1734ES6-4.2#TRPBF can charge NiMH batteries by grounding the BAT pin to disable the 4.2V voltage regulation loop, leaving only the constant-current loop active. In this configuration, it functions as a programmable current source (50–700mA) with PROG-based current monitoring-ideal for NiMH applications requiring controlled CC charge without CV termination, as specified in the LTC1734ES6-4.2#TRPBF datasheet.

What is the maximum allowable R_PROG value for stable operation of the LTC1734ES6-4.2#TRPBF?

The LTC1734ES6-4.2#TRPBF supports R_PROG values up to approximately 30kΩ for reliable 50mA full-scale current, but stability degrades above this due to pole frequency reduction. For optimal AC stability and current-monitoring accuracy, Analog Devices recommends minimum full-scale currents of 200mA (R_PROG = 7.5kΩ) and strict limitation of capacitive loading on the PROG pin-verified in the LTC1734ES6-4.2#TRPBF application notes.

Does the LTC1734ES6-4.2#TRPBF require an external blocking diode, and why or why not?

No, the LTC1734ES6-4.2#TRPBF does not require an external blocking diode because its internal architecture prevents reverse current flow from battery to input when V_CC is absent. The DRIVE pin disconnects the PNP base from V_CC in sleep mode, and the BAT pin's internal divider is disabled-ensuring negligible battery drain (<1µA) and eliminating forward-voltage loss and thermal concerns associated with discrete diodes in the LTC1734ES6-4.2#TRPBF design.