LT1513/LT1513-2 SEPIC Constant- or Programmable-Current/ Constant-Voltage Battery Charger UFEATURESDESCRIPTION ■ Charger Input Voltage May Be Higher, Equal to or The LT®1513 is a 500kHz current mode switching regula- Lower Than Battery Voltage tor specially configured to create a constant- or program- ■ Charges Any Number of Cells Up to 20V mable-current/constant-voltage battery charger. In addition ■ 1% Voltage Accuracy for Rechargeable Lithium to the usual voltage feedback node, it has a current sense Batteries feedback circuit for accurately controlling output current ■ 100mV Current Sense Voltage for High Efficiency of a flyback or SEPIC (Single-Ended Primary Inductance (LT1513) Converter) topology charger. These topologies allow the ■ 0mV Current Sense Voltage for Easy Current current sense circuit to be ground referred and completely Programming (LT1513-2) separated from the battery itself, simplifying battery switch- ■ Battery Can Be Directly Grounded ing and system grounding problems. In addition, these ■ 500kHz Switching Frequency Minimizes topologies allow charging even when the input voltage is Inductor Size lower than the battery voltage. The LT1513 can also drive ■ Charging Current Easily Programmable or Shut Down a CCFL Royer converter with high efficiency in floating or U grounded mode. APPLICATIONS Maximum switch current on the LT1513 is 3A. This allows ■ Charging of NiCd, NiMH, Lead-Acid or Lithium battery charging currents up to 2A for a single lithium-ion Rechargeable Cells cell. Accuracy of 1% in constant-voltage mode is perfect ■ Precision Current Limited Power Supply for lithium battery applications. Charging current can be ■ Constant-Voltage/Constant-Current Supply easily programmed for all battery types. ■ Transducer Excitation , LTC and LT are registered trademarks of Linear Technology Corporation. ■ Universal Input CCFL Driver UTYPICAL APPLICATIONMaximum Charging Current WALL L1A* • 2.4 ADAPTER C2** + C3 7 INPUT 4.7µF D1† 2.2 SINGLE Li-Ion CELL 22µF VIN 5 V 25V SW 1.25A 2.0 (4.1V) 1.8 CHARGE DOUBLE Li-Ion LT1513 L1B* R1 CELL (8.2V) SYNC 1.6 6 2 • AND/OR S/S VFB 1.4 SHUTDOWN SHUTDOWN GND V I C1 C FB + 12V R4 R2 22µF 4 TAB 1 3 39Ω 25V CURRENT (A) 1.2 16V × R5 2 1.0 270Ω 20V C4 R3 0.8 C5 0.22µF 0.08Ω 0.1µF 0.6 BATTERY VOLTAGE LT1513 • TA01 0.4 * L1A, L1B ARE TWO 10µH WINDINGS ON A 0 5 10 15 20 25 30 COMMON CORE: COILTRONICS CTX10-4 INPUT VOLTAGE (V) ** CERAMIC MARCON THCR40EIE475Z OR TOKIN 1E475ZY5U-C304 INDUCTOR = 10µH † MBRD340 OR MBRS340T3. MBRD340 HAS 5µA TYPICAL ACTUAL PROGRAMMED CHARGING CURRENT WILL BE LEAKAGE, MBRS340T3 50µA TYPICAL INDEPENDENT OF INPUT VOLTAGE IF IT DOES NOT EXCEED VALUES SHOWN LT1513 • TA02 Figure 1. SEPIC Charger with 1.25A Output Current sn1513 1513fas 1