9-86; Rev 0; 0/00 MAX757/MAX758 Evaluation Kits General Description The MAX757/MAX758 evaluation kits (EV kits) are assembled and tested PC boards that implement a step-down, switching lithium-ion (Li+) battery charger. The MAX757 EV kit can be set to charge - to -series cells, and the MAX758 EV kit can be set to charge - to 4-series cells. The cell voltage can be set between 4.0V and 4.4V using standard resistors while maintaining overall regulation voltage accuracy. Three LEDs indicate the charging status. The MAX757/MAX758 EV kits detect faulty cells and terminate charging. Two capacitors are used to set the charge termination, prequalification, and fault timeout periods. A user-supplied thermistor may be connected to either EV kit to monitor battery temperature and suspend charging for over-/undertemperature conditions. DESIGNATION QTY DESCRIPTION C, C, C, C7, C4, C7, C8 7 C4 C5, C6, C9 C8, C9 C0, C C C C5, 50V X7R ceramic capacitors (0805) Murata GRM40-04X7R04K050 or Taiyo Yuden UMKBJ04KG µf, 0V X7R ceramic capacitor Taiyo Yuden LMKBJ05MG or Murata GRM40X7R05K0 000pF, 50V X7R ceramic capacitors, 50V X7R ceramic capacitors (06) µf, 5V, 0.00Ω, low-esr tantalum capacitors AVX TPSE6M05R000 or Kemet T495X6M05AS 0.µF, 50V X7R ceramic capacitor Taiyo Yuden UMK6BJ4ML 4.7µF, 0V X5R ceramic capacitor Taiyo Yuden LMK6BJ475ML or Murata GRM4-6X5R475K0 68µF, 0V, 0.50Ω, low-esr tantalum capacitor AVX TPSE686M00R050 Features Complete Li+ Charging Solution up to -Series Cells (MAX757) and 4-Series Cells (MAX758).5A Battery-Charging Current Low Heat/High Efficiency 00kHz PWM Operation Up to 4V Input Voltage Range (MAX757) Up to 8V Input Voltage Range (MAX758) 8-Pin SSOP Package Surface-Mount Construction Fully Assembled and Tested Ordering Information PART IC PACKAGE MAX757EVKIT 8 SSOP MAX758EVKIT 8 SSOP Component List DESIGNATION QTY DESCRIPTION D, D Diodes, N448-type Fairchild MMSD448, Vishay Liteon/Diodes, Inc. N448W, or General Semiconductor N448W D, D4 Schottky diodes, A, 0V Nihon ECQS0L or Vishay Liteon/Diodes, Inc. B0A JU -pin header JU -pin header JU -pin header (MAX757 EV kit) 4-pin header (MAX758 EV kit) L µh,.5a inductor Sumida CDRH04R-0NC LED, LED Light-emitting diodes (green), T LED Light-emitting diode (red), T R 0.05Ω ±, 0.5W sense resistor Dale WSL-00-R050F or IRC LRC-LR00-0-R050-F R, R 0kΩ ±5% resistors R R6 0 Not installed R7, R8 00kΩ ± resistors R9, R0, R Ω ±5% resistors R, R4 4.7Ω ±5% resistors U MAX757EAI (MAX757 EV kit) MAX758EAI (MAX758 EV kit) Maxim Integrated Products For price, delivery, and to place orders, please contact Maxim Distribution at -888-69-464, or visit Maxim s website at www.maxim-ic.com.
Quick Start The MAX757/MAX758 EV kits are fully assembled and tested surface-mount boards. Follow the steps below to verify board operation. Do not turn on the power supply until all connections are completed. Observe all precautions on the battery manufacturer s data sheet. Use only lithium-ion (Li+) cells with this charger: ) Set jumper JU to indicate the number of cells in the battery pack (Table ). ) Place a shunt on jumper JU to disable the temperature monitoring functions. ) Place a shunt across pins on JU to enable the MAX757 or MAX758. 4) For the MAX757, connect a +7VDC to +4VDC power supply with sufficient power rating across the VIN and GND pads. For the MAX758, connect a +7VDC to +8VDC power supply with sufficient power rating across the VIN and GND pads. 5) Connect a lithium-ion (Li+) battery pack between the BATT+ and BATT- pads. 6) Turn on the power supply. 7) Verify that LEDs,, and indicate the correct charging status. Detailed Description When battery charging is initiated, the charger enters the prequalification state. In this state, the batteries are charged at /0 of the programmed current limit while the charger measures the battery to determine if it can be charged. If the battery voltage is above.5v per cell, charging begins. At this time, the batteries are charged at a constant current (fast-charge state) or a constant voltage (full-charge state). The charger exits the full-charge state and enters the top-off state once the battery current drops to 0% of the fast-charge current, or the fast-charge timer expires. The charger remains in the top-off state for 45 minutes, after which charging is terminated. Once charging is terminated, if the battery voltage drops 5% from the fully charged voltage, charging automatically restarts. If at any time during charging, the thermistor input senses a temperature below 0 C or above +50 C, charging suspends until the temperature returns to a safe level. This kit is shipped with a 0kΩ resistor to disable the temperature monitoring function. If temperature monitoring is required, connect the appropriate thermistor (see Jumper Selection section). If the charger is unable to enter the fast-charge or fullcharge states, charging is terminated and the fault LED (red) lights to indicate a faulty battery. For more information on the operation of the MAX757 or MAX758, refer to the Detailed Description sections of the MAX757 and MAX758 data sheets. Charging Status The three LEDs on the EV kit indicate the charging status: LED (FULL) indicates that the battery pack is being charged with a constant voltage. LED (FAST) indicates that the battery pack is being charged with a constant current. LED (FAULT) indicates that charging terminated abnormally. Charging Current The voltage at the ISETOUT pin sets the charging current to the battery. The MAX757/MAX758 EV kits are shipped with ISETOUT connected to REF. This sets the charging current to the full-scale value of.5a. To change the charging current to a lower value, cut the trace shorting the two pads of R and install resistors for R and R4. Use the equations below to calculate the resistor values: I CHG = (R4 / (R + R4)) x.5a R = ((.5A / I CHG ) - ) x R4 Use 00kΩ for R4. Input Current The input current limit is set by sense resistor R and by the voltage applied to the ISETIN pin. This sets the input current limit to A (00mV/50mΩ). The MAX757/MAX758 EV kits are shipped with ISETIN connected to REF and a 50mΩ sense resistor. To change the input current limit to a lower value, cut the trace shorting the two pads of R5 and install resistors for R5 and R6. Use the equations below to calculate the resistor values: I IN = (R6 / (R5 + R6)) x A R5 = ((A / I IN ) - ) x R6 Use 00kΩ for R6. To further increase the input current limit, reduce the value of sense resistor R.
Table. Jumper Selection JUMPER JU JU JU JUMPER POSITION Closed* * * 4 FUNCTION before connecting a thermistor from THERM to GND pads. Bypasses THERM with a 0kΩ resistor. SHDN = high. M AX 757/M AX 758 enabled. SHDN = low. M AX 757/M AX 758 disabled. Drive SHDN pad with an external signal. CELL = GND. Cell count =. CELL =. Cell count = 4. (MAX758 only) CELL = REF. Cell count =. Component Suppliers SUPPLIER PHONE FAX AVX 80-946-0690 80-66- BC Components 80-77-500 Dale-Vishay 40-564- 40-56-648 Fairchild 408-8-000 408-8-0 General Semiconductor International Resistive Co. (IRC) 6-847-000 6-847-6 0-- 0-- Kemet 408-986-044 408-986-44 Murata 84-7-4 84-8-0490 Nihon 66-867-555 66-867-698 Sumida 847-956-0666 847-956-070 Taiyo Yuden 408-57-450 408-57-459 Vishay Liteon/Diodes, Inc. 805-446-4800 805-446-4850 Note: Please indicate that you are using the MAX757 or MAX758 when contacting these manufacturers. *Default position CELL = Float. Cell count =. Jumper Selection Jumper JU connects the thermistor input (THERM) to GND through a 0kΩ resistor, disabling temperature qualification. To enable temperature qualification (charging between 0 C and +50 C), remove the shunt from JU and connect a thermistor (BC Components part # -640-60 or equivalent) to the THERM and GND pads. For more information, refer to the MAX757 and MAX758 data sheets. The EV kits can be placed in shutdown mode using jumper JU. (See Table for jumper settings.) Jumper JU selects the number of series cells to be charged. (See Table for jumper settings.)
THERM SHDN *MAX758 ONLY JU R 0k C * JU 4 C R 0k C R (SHORTED BY PCB TRACE) R5 (SHORTED BY PCB TRACE) R7 00k JU C9 000pF C4 µf R4 OPEN R6 OPEN R8 00k C5 000pF C6 000pF 4 4 5 5 7 7 THM CCI CCS CCV REF ISETOUT ISETIN VADJ CELL SHDN TIMER TIMER U MAX757 MAX758 DCIN CSSP CSSN HSD HSD LX LX 8 7 6 9 0 9 0 D C7 R 4.7Ω C8 R4 4.7Ω C9 + C0 µf 5V + C µf 5V D R 0.05Ω C 0.µF VIN SYSTEM LOAD BST D C4 D4 L µh C 4.7µF PGND 8 GND CS C7 BATT FULLCHG 8 6 R9 LED C8 + C5 68µF BATT+ BATT- FASTCHG 5 R0 LED GND 6 FAULT 4 R LED Figure. MAX757/MAX758 EV Kit Schematic 4
.0".0" Figure. MAX757/MAX758 EV Kit Component Placement Guide Component Side Figure. MAX757/MAX758 EV Kit PC Board Layout Component Side.0" Figure 4. MAX757/MAX758 EV Kit PC Board Layout Solder Side Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 0 San Gabriel Drive, Sunnyvale, CA 94086 408-77-7600 5 000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.