LTC4085

PRODUCTION

USB Power Manager with Ideal Diode Controller and Li-Ion Charger

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Overview

  • Seamless Transition Between Input Power Sources: Li-Ion Battery, USB and 5V Wall Adapter
  • 215mΩ Internal Ideal Diode Plus Optional External Ideal Diode Controller Provide Low Loss PowerPath™ When Wall Adapter/USB Input Not Present
  • Load Dependent Charging Guarantees Accurate USB Input Current Compliance
  • Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charging Rate Without Risk of Overheating
  • Selectable 100% or 20% Input Current Limit (e.g., 500mA/100mA)
  • Battery Charge Current Independently Programmable Up to 1.2A
  • Preset 4.2V Charge Voltage with 0.8% Accuracy
  • C/10 Charge Current Detection Output
  • NTC Thermistor Input for Temperature Qualified Charging
  • Tiny (4mm × 3mm × 0.75mm) 14-Lead DFN Package

The LTC4085 is a USB power manager and Li-Ion battery charger designed for portable battery-powered applications. The part controls the total current used by the USB peripheral for operation and battery charging. The total input current can be limited to 20% or 100% of a programmed value up to 1.5A (typically 100mA or 500mA). Battery charge current is automatically reduced such that the sum of the load current and charge current does not exceed the programmed input current limit.

The LTC4085 includes a complete constant-current/constant-voltage linear charger for single cell Li-ion batteries. The float voltage applied to the battery is held to a tight 0.8% tolerance, and charge current is programmable using an external resistor to ground. An end-of-charge status output CHRG indicates full charge. Total charge time is programmable by an external capacitor to ground. When the battery drops 100mV below the float voltage, automatic recharging of the battery occurs. Also featured is an NTC thermistor input used to monitor battery temperature while charging.

The LTC4085 is available in a 14-lead low profile 4mm × 3mm DFN package.

Float Voltage (V) NTC Hot Threshold Undervoltage Current Limit
LTC4085 4.2V 29% Vvntc Yes
LTC4085-1 4.1V 32.6% Vvntc Yes
LTC4085-3 3.95V 32.6% Vvntc Yes
LTC4085-4 3.95V 32.6% Vvntc No

Applications

  • Portable USB Devices: Cameras, MP3 Players, PDAs
LTC4085
USB Power Manager with Ideal Diode Controller and Li-Ion Charger
Input and Battery Current vs Load Current RPROG = 100k, RCLPROG = 2k Product Package 1
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 1

Data Sheet

This is the most up-to-date revision of the Data Sheet.

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Interface Transceivers & Isolators 1
LTM2884
PRODUCTION Isolated USB Transceiver with Isolated Power
Protection Switches & Controllers 1
LTC4361-1
LTC4361-2
Overvoltage/Overcurrent Protection Controller
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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

  • LTC4085
  • LTC4085-1
  • LTC4085-3
  • LTC4085-4
LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

Evaluation Kits

eval board
schematic 1
DC937A

LTC4085EDE Demo Board | 700mA CC/CV Li-Ion Linear Charger, VIN = 4.5V to 5.5V

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Product Details

Demonstration circuit DC937A is a complete power controller for a USB powered device. It is based on the LTC4085 and provides a constant-current, constant-voltage linear battery charger, a USB power manager with PowerPath management for the battery. The 700mA CC/CV timer terminated, temperature qualified, linear charger targets Li-Ion batteries, and the USB power manager insures compliance with the USB power specification and PowerPath management for the battery. The demo board's input voltage range is 4.5V to 5.5V.


 
DC937A
LTC4085EDE Demo Board | 700mA CC/CV Li-Ion Linear Charger, VIN = 4.5V to 5.5V
DC937A - Schematic

Latest Discussions

2 Years Ago
LTC4085 - USB Power Manage
2 Years Ago
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2 Years Ago
LTC4085 - USB power manager and Li-Ion battery charger
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