Analog Devices Inc. LTC4067EDE#PBF

LTC4067EDE#PBF Product Summary

The LTC4067EDE#PBF from Analog Devices is a highly integrated USB power manager and single-cell Li-Ion/Li-Polymer battery charger housed in a compact 12-lead 4mm × 3mm DFN package. Designed specifically for portable systems, the LTC4067EDE#PBF optimizes power management and charging efficiency for products that rely on USB or wall adapter inputs. Key applications include automatic battery charging with load switchover, backup battery charging, and uninterrupted power supplies where reliability and compliance with USB power standards are critical.

Primary Attributes and Advantages of the LTC4067EDE#PBF

The LTC4067EDE#PBF delivers a blend of essential features required for miniaturized, robust power management:

Programmable input current limit via a single resistor at the CLPROG pin, enabling compliance with USB low/high power modes.

Complete linear charging solution for single-cell Li-Ion or Li-Polymer batteries up to 1.25A programmable charge current with precise 4.2V battery float voltage.

Advanced PowerPath™ control for seamless automatic switching between input sources and battery power via an internal ideal diode.

13V overvoltage input protection with an external P-channel MOSFET for robust safety against accidental high-voltage adapter connections.

NTC thermistor input for battery temperature-qualified charging, including fault signaling using the CHRG pin.

Integrated safety features: thermal regulation for overtemperature protection, a two-hour safety timer for charge termination, and bad battery timeout detection.

Ultra-low power shutdown and suspend operation for compliance with USB standards and enhanced battery longevity.

These features collectively make the LTC4067EDE#PBF an attractive solution for engineers seeking USB-compliant designs with high charging efficiency, system load prioritization, and extensive protection mechanisms.

LTC4067EDE#PBF Electrical Parameters and Performance Boundaries

A comprehensive understanding of the device’s limits ensures robust design and risk mitigation:

Absolute maximum voltages: IN, OUT, BAT pins: –0.3V to 7V (transient), –0.3V to 6V (steady state).

OVI and OVP: –0.3V to 13V to accommodate overvoltage events with protection MOSFETs.

Operating temperature: –40°C to +85°C.

Maximum programmable input and charge currents: input current up to 1.5A (typically 500mA for USB high-power configurations), charge current programmable up to 1.25A (accuracy may degrade above 1A).

Package thermal characteristics: θJA = 43°C/W with the exposed paddle connected to PCB ground for effective heat dissipation.

Device shutdown minimizes standby current to less than 20μA, extending battery runtime.

Pin Descriptions and Block Diagram Overview for the LTC4067EDE#PBF

The signal and power pins are tightly integrated to streamline board-level design:

CLPROG: Programs/monitors input current limit through a precise resistor; key for USB compliance.

CHRG: Open-drain status/fault output; supports LED and microcontroller interface for charge and fault indication.

NTC: Thermistor sensor input for charge qualification based on battery temperature.

ILIM0/ILIM1: Select active current limit mode (including suspend, low, high, and disable modes).

OVI/OVP: Interface for input overvoltage protection with an external P-channel MOSFET.

PROG: Sets charge current; can also serve as a hardware enable for the device.

OUT: Main system output, powers application load and charger.

BAT: Connects directly to the single Li-Ion cell.

GATE: Drives optional external ideal diode PFET for increased conductance in high-power applications.

IN: USB or adapter input power.

Exposed Pad: Must be solidly grounded for electrical and thermal performance.

The block diagram centers around a PowerPath controller, ideal diode, charge control, thermal/NTC protection, and overvoltage circuitry.

In-depth Operational Description of the LTC4067EDE#PBF

The LTC4067EDE#PBF intelligently balances system load and battery charging current, strictly observing the programmed input current limit for USB compliance:

With external power, OUT feeds the application load and charges the battery; system load is always prioritized over charging current.

If the total OUT (load + charger) current would exceed the programmed limit, the charger’s current is automatically reduced while ensuring loads remain powered.

The internal ideal diode guarantees seamless switchover from input power to battery power should the input be removed or overloaded—without voltage droop or interruption.

Overvoltage protection is enabled with an external PFET, disconnecting IN during excessive voltages to safeguard the LTC4067EDE#PBF and battery.

The battery charger employs a constant current (CC) and constant voltage (CV) algorithm with 4.2V float, automatic trickle charge for deep discharge, fast charge with charge termination after two hours in CV mode, and recharge maintenance below 4.1V.

Safety is reinforced with a battery NTC thermistor input, which halts charging if temperature is unsafe, signaled by flashing pulses at the CHRG output.

System enter low-power shutdown or USB suspend operation when configured via the PROG or current-limit control pins; all active circuits are disabled to conserve energy.

Use Cases and Reference Designs Featuring the LTC4067EDE#PBF

The most common applications for the LTC4067EDE#PBF include:

Charging single-cell Li-Ion batteries from both USB and dedicated wall adapters in portable devices.

Power backup systems for uninterrupted operation in handhelds, industrial terminals, and medical instrumentation.

USB peripherals requiring strict compliance with power draw specifications regardless of variable system load or charge state.

Use in designs where robust adapter overvoltage protection is mandatory (e.g., environments where users may inadvertently connect incorrect chargers).

Intelligent load-sharing scenarios, such as when a high-efficiency switching regulator is powered from the OUT pin to maximize available battery charge.

Two typical design use cases:

1) A single-cell Li-Ion charger for a wall adapter, with input current limit and overvoltage protection.

2) A USB-powered charger for portable equipment, automatically distinguishing between low- and high-power USB host modes and handling suspend conditions.

Thermal Management, Reliability, and PCB Layout Guidelines for the LTC4067EDE#PBF

Effective deployment of the LTC4067EDE#PBF depends on solid thermal management and stable analog performance:

The exposed pad must be soldered to the PCB ground for optimal thermal conduction, leveraging the 43°C/W thermal resistance.

The charger is thermally regulated; die temperature is limited to approximately 105°C by automatic reduction of charge current in high-power conditions. This allows charge setting according to real operating environments rather than ‘worst-case’ derating.

For charger stability, maintain short, low-inductance battery leads; add a 1μF bypass capacitor at the BAT pin where needed.

The PROG pin should avoid excess capacitance to maintain control loop bandwidth; in designs, add a series resistor when filtering is needed for measurement.

For USB compliance, select CLPROG values appropriately and decouple critical power pins with multi-layer ceramic capacitors (IN: ≥1μF, OUT: ≥10μF).

System designers must ensure that any external MOSFETs (for OVP or ideal diode functions) have suitable on-resistance and gate charge, as described in the datasheet’s recommendations.

Alternative or Substitute Options Comparable to the LTC4067EDE#PBF

Selecting an alternative to the LTC4067EDE#PBF depends on specific application needs—such as package size, USB power compliance, maximum charge current, and overvoltage protection. Key comparable products from Analog Devices (formerly Linear Technology) and other industry manufacturers include:

LTC4055: A similar USB power manager/charger without the external OVP capability, suited for small form factor devices.

LTC4085: Offers higher input current and enhanced power path control, with additional USB OTG features.

MAX8903 (Maxim Integrated): Dual input (USB and wall adapter) charger with PowerPath control for single-cell Li-Ion cells.

bq2407x series (Texas Instruments): Single-cell USB-compliant chargers featuring PowerPath management and robust fault protection.

Engineers may consider these or other models depending on secondary requirements such as interface, maximum charge current, pin compatibility, feature set, and regulatory standards. For drop-in replacement emphasis, consult detailed datasheets and qualification reports.

Conclusion

: Selecting the LTC4067EDE#PBF for advanced power path and charging designs

The Analog Devices LTC4067EDE#PBF provides a refined, proven solution for engineers needing advanced USB power management with single-cell Li-Ion battery charging. Its programmability, robust protection suite, automatic switchover, and compact footprint support demanding portable and backup applications. Factoring in the device's flexibility, comprehensive protection, and ease of integration, the LTC4067EDE#PBF stands out as a compelling choice for next-generation portable power designs. For those seeking to maximize system safety, charging efficiency, and form factor advantages, the LTC4067EDE#PBF merits careful consideration at the product selection and design-in phase.