LT1512 - SEPIC Constant-Current/Constant-Voltage Battery Charger

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.

Maximum switch current on the LT1512 is 1.5A. This allows battery charging currents up to 1A 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.

Features
  • Charger Input Voltage May Be Higher, Equal to or
  • Lower Than Battery Voltage
  • Charges Any Number of Cells Up to 30V*
  • 1% Voltage Accuracy for Rechargeable Lithium Batteries
  • 500kHz Switching Frequency Minimizes Inductor Size
  • 100mV Current Sense Voltage for High Efficiency
  • Battery Can Be Directly Grounded
  • Charging Current Easily Programmable or Shut Down
Typical Application

Applications
  • Battery Charging of NiCd, NiMH, Lead-Acid or Lithium Rechargeable Cells
  • Precision Current Limited Power Supply
  • Constant-Voltage/Constant-Current Supply
  • Transducer Excitation
Packaging
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LT1512CGN#PBFSSOP-16C$5.25$4.25
LT1512CGN#TRPBFSSOP-16C$4.31
LT1512CN8#PBFN-8C$4.50$3.60
LT1512CS8#PBFSO-8C$4.65$3.75
LT1512CS8#TRPBFSO-8C$3.81
LT1512IGN#PBFSSOP-16I$5.90$4.80
LT1512IGN#TRPBFSSOP-16I$4.86
LT1512IN8#PBFN-8I$5.15$4.15
LT1512IS8#PBFSO-8I$5.35$4.25
LT1512IS8#TRPBFSO-8I$4.31
Datasheet
Spec Notice
Application Note
Design Note
Reliability Data
LT Journal
LTspice
Related Product
LT1512 - SEPIC Constant-Current/ Constant-Voltage Battery Charger
LT1512 - SPECIFICATION NOTICE
AN84 - Linear Technology Magazine Circuit Collection, Volume IV
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R324 Reliability Data
Jun 1999 Low Voltage PowerPath Driver Switches from a 3.3V or 5V Supply to Battery Backup
LT1512 Footprints and Symbols
LT1512 Demo Circuit - SEPIC Charger with 0.5A Output Current (5-25V to 5.2V @ .5A)