Analog Devices Inc. LTC1734LES6-4.2#TRPBF

Overview

LTC1734LES6-4.2#TRPBF from Analog Devices (formerly Linear Technology) is a single-cell Li-ion linear battery charger controller in SOT-23 package, delivering 50–180 mA programmable constant current and 4.2 V ±1% float voltage with PROG-pin current monitoring. It integrates undervoltage lockout, thermal/overcurrent protection, manual shutdown, and automatic sleep mode for portable power management in space-constrained devices.

For engineers reviewing the LTC1734LES6-4.2#TRPBF datasheet, LTC1734LES6-4.2#TRPBF pinout, LTC1734LES6-4.2#TRPBF application, or LTC1734LES6-4.2#TRPBF equivalent, key selection criteria include external PNP pass transistor compatibility, PROG-resistor-based current programming accuracy, BAT-pin voltage sensing stability, and zero-battery-drain behavior in shutdown/sleep modes.

Technical Context

The LTC1734LES6-4.2#TRPBF implements dual-loop control: a constant-current loop using 250:1 current mirroring from ISENSE to PROG (1.5 V reference), and a constant-voltage loop comparing a precision 2.5 V internal reference against a 4.2 V battery voltage divided by an on-chip resistor network. It requires no external sense resistor or blocking diode.

Its operation relies on an external PNP pass transistor driven via the DRIVE pin; charge current is set by R_PROG between PROG and GND (IBAT ≈ 375 / R_PROG), while real-time monitoring is enabled by V_PROG = IBAT × R_PROG / 250. UVLO activates below 4.56 V (typ), with 150 mV hysteresis, and thermal protection limits junction temperature to 125°C.

Key Specifications

Pinout & Package

Package: 6-lead SOT-23 (ThinSOT™), 1 mm profile, surface-mount compatible. RoHS-compliant, lead-free, tape-and-reel (TRPBF).

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 LTC1734LES6-4.2#TRPBF offers unique design flexibility through external PNP selection, precise analog current monitoring, and ultra-low battery drain-making it optimal for low-power, thermally sensitive, or cost-sensitive linear charger implementations where discrete pass transistor optimization is critical.

Availability

LTC1734LES6-4.2#TRPBF is available at Aetrix Electronics and suitable for smartphone charging circuits, digital camera power management, wireless headset battery chargers, portable medical sensor modules, and low-cost portable electronics requiring stable component supply and long-term lifecycle support.

Supply support for LTC1734LES6-4.2#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 legacy precision analog portfolio, including high-performance power management ICs designed for reliability, accuracy, and low-noise operation.

The LTC1734L product line delivers compact, low-cost linear Li-ion charger controllers targeting portable consumer and industrial devices where simplicity, minimal external components, and zero-battery-drain shutdown are essential design goals.

FAQ

What is the maximum charge current supported by the LTC1734LES6-4.2#TRPBF?

The LTC1734LES6-4.2#TRPBF supports a maximum programmed charge current of 180 mA, achieved with a 2.1 kΩ program resistor (R_PROG). This assumes adequate thermal design and a PNP transistor with β > 50 and sufficient power dissipation capability. The absolute maximum I_SENSE rating is –210 mA, but sustained operation above 180 mA is not recommended due to thermal limitations and specification guarantees.

Does the LTC1734LES6-4.2#TRPBF require an external blocking diode?

No, the LTC1734LES6-4.2#TRPBF does not require an external blocking diode. Its architecture uses an external PNP pass transistor configured in high-side mode, which inherently prevents reverse current flow from battery to input when VCC is absent. This eliminates diode forward-voltage drop and associated power loss, improving efficiency and simplifying bill-of-materials.

How is charge termination implemented using the LTC1734LES6-4.2#TRPBF?

Charge termination is implemented externally using the PROG pin voltage: V_PROG = IBAT × R_PROG / 250. A microcontroller's ADC reads V_PROG to determine real-time charge current; when current drops to ~10% of the programmed value (e.g., 5 mA for 50 mA setting), the MCU can assert manual shutdown. The LTC1734LES6-4.2#TRPBF itself does not auto-terminate but provides precise analog feedback for intelligent system-level control.

What is the function of the BAT pin on the LTC1734LES6-4.2#TRPBF?

The BAT pin on the LTC1734LES6-4.2#TRPBF serves as the precision battery voltage sense input. An internal resistor divider references the 4.2 V float voltage to a 2.5 V internal bandgap, enabling accurate constant-voltage regulation. It draws ~34 µA during charging and must be connected with minimal series resistance and ≥5 µF bypass capacitance to ensure stability and avoid float voltage error.

Can the LTC1734LES6-4.2#TRPBF be used to charge NiMH batteries?

Yes, the LTC1734LES6-4.2#TRPBF can charge NiMH batteries by grounding the BAT pin to disable the constant-voltage loop, converting it into a pure constant-current source. Charge current remains programmable via R_PROG (50–180 mA range), and termination must be handled externally-e.g., via –ΔV detection or timer-since the IC lacks NiMH-specific algorithms or temperature monitoring interfaces.