Analog Devices Inc. LTC4056ETS8-4.2#TRPBF

Overview

LTC4056ETS8-4.2#TRPBF from Analog Devices (formerly Linear Technology) is a single-cell Li-Ion battery charger controller IC that implements constant-current/constant-voltage charging with programmable termination timer, ±0.6% float voltage accuracy (4.2 V), and 700 mA max charge current. It requires only one external resistor (R_PROG) and capacitor (C_TIMER) to configure charge parameters and integrates trickle charge, undervoltage current limiting, automatic recharge, and CHRG status output - used in compact USB-powered portable chargers.

For engineers reviewing the LTC4056ETS8-4.2#TRPBF datasheet, LTC4056ETS8-4.2#TRPBF pinout, LTC4056ETS8-4.2#TRPBF application, or LTC4056ETS8-4.2#TRPBF equivalent, key selection considerations include its 8-pin SOT-23 package, external PNP pass transistor requirement, 4.5–6.5 V input range, 40 µA shutdown supply current, and absence of internal power switch or sense resistor.

Technical Context

The LTC4056ETS8-4.2#TRPBF operates as a linear controller driving an external PNP pass transistor, using dual feedback loops: a constant-current loop referenced to the PROG pin's 1.0 V virtual ground (ICHG ≈ 915 × V_PROG/R_PROG), and a constant-voltage loop comparing a precision 1.2 V internal reference against a divided BAT voltage. It features integrated undervoltage lockout (4.325–4.475 V rising threshold) and undervoltage charge current limiting (V_UVCL ≈ 4.575 V).

Charge state management includes programmable timer-based termination (±12% accuracy), automatic recharge at ~4.05 V, and three-phase operation: trickle charge (<2.8 V), full CC mode (2.9–4.05 V), and CV mode (≥4.05 V). Shutdown and sleep modes reduce battery drain to <1 µA, with manual shutdown triggered by pulling TIMER/SHDN below 0.6–1.0 V.

Key Specifications

Pinout & Package

Package: 8-lead SOT-23 (ThinSOT™), 1 mm profile, RoHS-compliant, rated for –40°C to +85°C ambient operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP73831T-2DCI/OT and BQ24075RGTR, the LTC4056ETS8-4.2#TRPBF offers superior flexibility in charge current tuning (200–700 mA), precise undervoltage behavior, and minimal battery drain (<1 µA), making it ideal for space-constrained, low-power, and high-reliability standalone chargers where external transistor control is acceptable.

Availability

LTC4056ETS8-4.2#TRPBF is available at Aetrix Electronics and suitable for USB-powered portable chargers, digital camera docks, handheld medical sensors, Bluetooth headset cases, and low-cost Li-Ion charging solutions requiring stable component supply and long-term manufacturability.

Supply support for LTC4056ETS8-4.2#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 of high-performance analog ICs, particularly in power management, signal conditioning, and precision timing.

The LTC4056ETS8-4.2#TRPBF belongs to Linear's Li-Ion charger controller product line, designed specifically for cost-sensitive, space-constrained, standalone charging applications where external pass transistor control delivers optimal thermal and efficiency trade-offs.

FAQ

What is the exact float voltage accuracy of the LTC4056ETS8-4.2#TRPBF?

The LTC4056ETS8-4.2#TRPBF regulates battery voltage to 4.200 V with guaranteed accuracy of ±0.6% (4.175 V to 4.225 V) under specified conditions (IBAT = 10 mA, TA = 25°C). Over the full –40°C to +85°C operating range, accuracy remains ±0.842% (4.158 V to 4.242 V), ensuring consistent Li-Ion cell health and capacity retention.

Does the LTC4056ETS8-4.2#TRPBF include an internal power switch?

No, the LTC4056ETS8-4.2#TRPBF does not include an internal power switch. It is a controller IC that drives an external PNP pass transistor (e.g., ZXT1M322 or FMMT720) via its DRIVE pin. This architecture allows thermal dissipation to be managed externally and supports higher current or custom voltage configurations beyond monolithic IC limitations.

How is charge current programmed on the LTC4056ETS8-4.2#TRPBF?

Charge current is programmed using a single resistor (R_PROG) between the PROG pin and GND. The LTC4056ETS8-4.2#TRPBF maintains a 1.0 V virtual reference at PROG, so ICHG ≈ 915 × (1 V / R_PROG). For example, R_PROG = 1.43 kΩ yields ~700 mA. Base current error can be compensated by reducing R_PROG by ~2% for β = 50 transistors.

What happens to the CHRG pin during different charge states of the LTC4056ETS8-4.2#TRPBF?

During active charging, the CHRG pin is strongly pulled low (≤0.4 V at 10 mA). Upon timer expiration or manual shutdown (with VCC > V_UVLOD), it transitions to a 12 µA weak pull-down. If VCC falls below ~4.275 V, CHRG goes high-impedance - enabling microcontroller detection of three distinct states: charging, terminated, or no input power.

Can the LTC4056ETS8-4.2#TRPBF operate from a 4.5 V USB source without issues?

Yes, the LTC4056ETS8-4.2#TRPBF operates from 4.5 V to 6.5 V, but charging begins only when VCC exceeds the undervoltage lockout rising threshold (4.325–4.475 V) and the undervoltage charge current limit threshold (~4.575 V). At 4.5 V, it may enter undervoltage current limiting - reducing ICHG to maintain stability - which is intentional for marginal USB sources.