Features

• Charger Input Voltage May Be Higher, Equal to or Lower Than Battery Voltage
• Charges Any Number of Cells Up to 20V
• 1% Voltage Accuracy for Rechargeable Lithium Batteries
• 100mV Current Sense Voltage for High Efficiency (LT1513)
• 0mV Current Sense Voltage for Easy Current Programming (LT1513-2)
• Battery Can Be Directly Grounded
• 500kHz Switching Frequency Minimizes Inductor Size
• Charging Current Easily Programmable or Shut Down

Typical Application

Description

The LT1513 is a 500kHz current mode switching regulator specially configured to create a constant- or programmable-current/constant-voltage battery charger. In addition to the usual voltage feedback node, it has a current sense feedback circuit for accurately controlling output current of a flyback or SEPIC (Single-Ended Primary Inductance Converter) topology charger. These topologies allow the current sense circuit to be ground referred and completely separated from the battery itself, simplifying battery switching and system grounding problems. In addition, these topologies allow charging even when the input voltage is lower than the battery voltage. The LT1513 can also drive a CCFL Royer converter with high efficiency in floating or grounded mode.

Maximum switch current on the LT1513 is 3A. This allows battery charging currents up to 2A for a single lithium-ion cell. Accuracy of 1% in constant-voltage mode is perfect for lithium battery applications. Charging current can be easily programmed for all battery types.