LT1512
SEPIC Constant-Current/
Constant-Voltage Battery Charger
Features Description Charger Input Voltage May Be Higher, Equal to or
Lower Than Battery Voltage
n Charges Any Number of Cells Up to 30V*
n 1% Voltage Accuracy for Rechargeable Lithium
Batteries
n 500kHz Switching Frequency Minimizes
Inductor Size
n 100mV Current Sense Voltage for High Efficiency
n Battery Can Be Directly Grounded
n Charging Current Easily Programmable or Shut Down The LT®1512 is a 500kHz current mode switching regulator
specially configured to create a constant-current/constantvoltage 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. n Applications Maximum switch current on the LT1512 is 1.5A. This allows …