DESCRIPTION
The LTC®4085-3/LTC4085-4 is a USB power manager and Li-Ion/Polymer 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.

FEATURES
■ Seamless Transition Between Input Power Sources:
   Li-Ion/Polymer 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
■ 3.95V Float Voltage Improves Battery Life Span and
   High Temperature Safety Margin
■ 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
■ Automatic Output Undervoltage Charge Current
   Reduction (LTC4085-3)
■ Tiny (4mm × 3mm × 0.75mm) 14-Lead DFN Package

APPLICATIONS
■ Portable USB Devices