Features and Benefits
- Charges Single Cell Li-Ion Batteries Directly from USB Port
- Load Dependent Charging Guarantees USB Input Current Compliance
- Automatic Battery Switchover When Input Supply is Removed
- Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charging Rate Without Risk of Overheating*
- Selectable 500mA/100mA Current Limit
- Low Loss Full PowerPath™ Control with Ideal Diode Operation (Reverse Current Blocking)
- Preset 4.2V Charge Voltage with 0.8% Accuracy (4.1V for LTC4055-1)
- 4.1V Float Voltage (LTC4055-1) Improves Battery Life and High Temperature Safety Margin
- USB-Compliant Suspend Mode
- Programmable Charge Current and Termination Timer
- Soft-Start Limits Inrush Current
- NTC Thermistor Input for Temperature Qualified Charging
- Tiny (4mm x 4mm x 0.75mm) QFN Package
The LTC4055/LTC4055-1 are USB power manager and Li-Ion battery chargers designed to work in portable battery-powered applications. The parts manage and limit the total current used by the USB peripheral for operation and battery charging. Depending on the state of the current select pin (HPWR), total input current can be limited to either 100mA or 500mA. The voltage drop from the USB supply or battery to the USB peripheral is typically less than 100mV at 400mA and 20mV at 80mA. Other management features include: automatic switch over to battery when input is removed, inrush current limiting, reverse current blocking, undervoltage lockout and thermal shutdown.
The LTC4055/LTC4055-1 include 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. Fully discharged cells are automatically trickle charged at 10% of the programmed current until the cell voltage exceeds 2.8V. 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 LTC4055/LTC4055-1 are available in a 16-pin low proﬁle (4mm x 4mm) QFN package.
- 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.
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.