Combination Battery Charger and DC/DC Converter

The LTC1980 integrates PWM power control for charging a battery and converting the battery voltage to a regulated output or simultaneously charging the battery while powering a system load from an unregulated AC wall adapter. Combining these features into a single IC produces a smaller area and lower cost solution compared to presently available multi-IC solutions. The LTC1980 shares the discrete components for both the battery charger and the DC/DC converter thus minimizing size and cost relative to dual controller solutions. Both the battery charger and DC/DC converter use a current mode flyback topology for high efficiency and excellent transient response. Optional Burst Mode operation and power-down mode allow power density, efficiency and output ripple to be tailored to the application.

The LTC1980 provides a complete Li-Ion battery charger with charge termination timer, preset Li-Ion battery voltages, overvoltage and undervoltage protection, and userprogrammable constant-current charging. Automatic battery recharging, shorted-cell detection, and open-drain C/10 and wall plug detect outputs are also provided. User programming allows NiMH and NiCd battery chemistries to be charged as well.

Applications

* Digital Cameras

* Handheld Computers

* Personal Digital Assistants

* 1W to 10W Uninterruptable Power Supplies

* Single Controller IC Includes Battery Charger Plus DC/DC Converter * Wall Adapter Voltage May be Above or Below Battery Voltage * LDO Controller Allows Simultaneous Charging and Regulating from Wall Adapter Input * Standalone Li-Ion Battery Charger Including Charge Termination, Overvoltage Protection, Shorted-Cell Detection and Battery Recharge * Selectable 4.1V, 4.2V, 8.2V and 8.4V Float Voltages * Simple NiMH and NiCd Battery Charger * Pin Programmable Regulator Burst Mode® Operation and Shutdown for High Efficiency * High Efficiency Current Mode 300kHz PWM * Reduced Component Architecture * Undervoltage Protection and Soft-Start Insures Start-Up with Current Limited Wall Adapter * Small 24-Pin SSOP Package