USB Power Manager requires no external control.

Press Release Summary:

Single-IC, autonomous power manager and battery charger, Model LTC4055 provides power to USB peripheral device and charges peripheral's single-cell Li-Ion battery from USB VBUS or wall adapter power supply. Unit automatically reduces battery charge current as system load current increases. Once power source is removed, current flows from battery to load through internal low loss diode. Float voltage is preset at 4.2 V with guaranteed 0.8% accuracy from 0-85°C.

Original Press Release:

Single-IC USB Power Manager & Battery Charger Requires No External Control

MILPITAS, CA - May 25, 2004 - Linear Technology Corporation introduces the LTC4055, a single-IC autonomous power manager and battery charger for USB and USB On-The-Go devices. The LTC4055 provides power to the USB peripheral device and charges the peripheral's single-cell Li-Ion battery from the USB VBUS or a wall adapter power supply if the adapter is present. To comply with USB current limit specifications, the LTC4055 automatically reduces battery charge current as the system load current increases. To ensure that a fully charged battery remains fresh when the bus is connected, the IC directs power to the load through the USB bus rather than extracting power from the battery. Once the power source is removed, current flows from the battery to the load through an internal low loss "ideal" diode, minimizing voltage drop and power dissipation.

The LTC4055 has the unique ability to detect the presence of a wall adapter and use it as an alternate power source to charge the battery while providing power to the load. The LTC4055 also offers the option of charging the battery at a higher rate (up to 1A) than USB specifications allow (100mA/500mA) when the wall adapter is present so that the battery can be charged much faster. Additional functions include charge termination timer, automatic recharge, NTC thermistor input, automatic switchover to battery when the AC adapter input is removed, inrush current limiting, reverse current blocking, undervoltage lockout and thermal regulation.

Furthermore, the LTC4055's float voltage is preset at 4.2V with guaranteed 0.8% accuracy from 0°C to 85°C. Charge current is easily programmed using a resistor. For battery pre-conditioning and qualification, fully discharged cells are automatically trickle charged at 10% of the programmed current until the cell voltage exceeds 2.8V. Total charge time for charge termination is programmed by an external capacitor. The LTC4055 is housed in a tiny 4mm x 4mm QFN package with a 0.8mm profile.

The LTC4055 is guaranteed for operation from -40°C to 85°C. 1,000-piece pricing starts at $2.20 each.

Summary of Features: LTC4055
Single-IC USB Power Manager & Battery Charger
Guaranteed USB Input Current Compliance
Automatic Battery Switchover
Thermal Regulation Prevents Overheating
Integrated "Ideal" Diode for Low Dropout & Low Power Loss
Simultaneous Operation from USB & Wall Adapter
Standalone Charger: Termination, Pre-Charge, Charge Control and Recharge.

Company Background
Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.

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