Analog Devices Inc. LTC4065EDC-4.4#TRPBF

Overview

LTC4065EDC-4.4 from Analog Devices (formerly Linear Technology) is a standalone linear lithium-ion battery charger IC designed for single-cell 4.4V Li-Ion batteries in portable electronics. It delivers up to 750mA constant-current/constant-voltage charging with ±0.6% float voltage accuracy, integrated thermal regulation at ~115°C, and C/10 charge termination detection - all in a 2mm × 2mm 6-lead DFN package. It operates directly from USB (4.5–5.5V) and supports automatic recharge, trickle charge, and shutdown mode.

For engineers reviewing the LTC4065EDC-4.4 datasheet, LTC4065EDC-4.4 pinout, LTC4065EDC-4.4 application, or LTC4065EDC-4.4 equivalent, key selection considerations include its 4.4V fixed float voltage, PROG-pin-based current programming, CHRG open-drain status output with defective-battery pulse mode, thermal-foldback behavior, and USB-compliant input voltage range with undervoltage charge limiting.

Technical Context

The LTC4065EDC-4.4 implements a three-loop control architecture: constant-current (CA), constant-voltage (VA), and constant-temperature (TA), with priority logic ensuring safe transition between modes. Its internal P-channel power FET (450mΩ typical R_ON) eliminates external MOSFETs, sense resistors, or blocking diodes.

Charge initiation requires V_CC > 3.6V and V_CC > V_BAT + 80mV; undervoltage lockout (UVLO) has 3.6V rising threshold with 0.6V hysteresis. Trickle charge activates below 2.9V BAT, and defective battery detection triggers after 1.125 hours of low-voltage condition, pulsing CHRG at 2Hz.

Key Specifications

Pinout & Package

Package: 6-lead plastic DFN (2mm × 2mm, 0.75mm height) with exposed thermal pad (Pin 7, GND). Must be soldered to PCB ground plane for rated thermal performance (θ_JA = 60°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ24075RGER and MAX1555ESA+, the LTC4065EDC-4.4 uniquely supports 4.4V Li-Ion cells with ±0.6% voltage accuracy, integrated thermal foldback, and PROG-pin-based real-time current monitoring - making it optimal for high-energy-density portable systems requiring autonomous, robust charging without host firmware involvement.

Availability

LTC4065EDC-4.4 is available at Aetrix Electronics and suitable for wireless PDAs, cellular phones, and portable medical monitors requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LTC4065EDC-4.4 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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC4065EDC-4.4 belongs to Linear's precision battery charger product line, engineered specifically for space-constrained, USB-powered portable devices using high-voltage (4.4V) lithium-ion cells - emphasizing integration, thermal resilience, and autonomous operation.

FAQ

What is the exact float voltage of the LTC4065EDC-4.4 and how accurate is it?

The LTC4065EDC-4.4 has a preset float voltage of 4.4V with ±0.6% accuracy (4.375V to 4.425V at 2mA load, 0°C to 85°C). This precision is achieved via an internal trimmed resistor divider on the BAT pin and does not require external components. The LTC4065EDC-4.4 is specifically designed for newer high-capacity 4.4V Li-Ion chemistries, distinguishing it from 4.2V chargers like the BQ24075.

How does the LTC4065EDC-4.4 handle thermal management during charging?

The LTC4065EDC-4.4 incorporates a dedicated constant-temperature (TA) feedback loop that begins reducing charge current when the junction temperature approaches ~115°C. This thermal foldback is fully autonomous - no external sensors or host intervention needed. The LTC4065EDC-4.4 continues charging at a reduced rate until temperature decreases, ensuring safe operation even in sealed enclosures or high ambient conditions.

Can the LTC4065EDC-4.4 be used with standard 4.2V Li-Ion batteries?

No - the LTC4065EDC-4.4 is factory-trimmed for 4.4V float voltage and is not compatible with standard 4.2V Li-Ion cells. Charging a 4.2V battery to 4.4V risks overvoltage, accelerated aging, and safety hazards. Use only with batteries explicitly rated for 4.4V maximum charge voltage, such as Sanyo UF553436T or UF553450T referenced in the datasheet.

What does the CHRG pin indicate, and what are its three operational states?

The CHRG pin on the LTC4065EDC-4.4 is an open-drain status output with three distinct states: (1) strong pull-down during active charging, (2) high-impedance when charge current falls to C/10, timer expires, or shutdown is active, and (3) 2Hz pulsed output (75% duty) if a defective battery is detected after 1.125 hours in trickle mode. This allows direct LED drive or GPIO monitoring without additional circuitry.

Does the LTC4065EDC-4.4 support USB enumeration or current limiting negotiation?

No - the LTC4065EDC-4.4 is a dumb charger with no USB protocol awareness. It draws up to 500mA from USB ports but does not perform USB-IF enumeration or negotiate higher currents (e.g., USB BC1.2 or USB PD). System designers must ensure host-side USB port compliance and implement external current limiting if required by USB specifications.