Features and Benefits
- 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|
- Portable USB Devices: Cameras, MP3 Players, PDAs
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
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.
Tools & Simulations
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.
Models for the following parts are available in LTspice:
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.