Evaluate: MAX1757/MAX1758 19-1816 Rev 0 10/00 MAX1757/MAX1758 Evaluation Kits General Description Features The MAX1757/MAX1758 evaluation kits (EV kits) are Complete Li+ Charging Solution up to 3-Series assembled and tested PC boards that implement a Cells (MAX1757) and 4-Series Cells (MAX1758) step-down, switching lithium-ion (Li+) battery charger. 1.5A Battery-Charging Current The MAX1757 EV kit can be set to charge 1- to 3-series Low Heat/High Efficiency cells, and the MAX1758 EV kit can be set to charge 1- to 4-series cells. The cell voltage can be set between 300kHz PWM Operation 4.0V and 4.4V using standard 1% resistors while main- Up to 14V Input Voltage Range (MAX1757) taining 1% overall regulation voltage accuracy. Three LEDs indicate the charging status. Up to 28V Input Voltage Range (MAX1758) The MAX1757/MAX1758 EV kits detect faulty cells and 28-Pin SSOP Package terminate charging. Two capacitors are used to set the Surface-Mount Construction charge termination, prequalification, and fault timeout periods. A user-supplied thermistor may be connected Fully Assembled and Tested to either EV kit to monitor battery temperature and sus- pend charging for over-/undertemperature conditions. Ordering Information PART IC PACKAGE MAX1757EVKIT 28 SSOP MAX1758EVKIT 28 SSOP Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY DESCRIPTION 0.1 F, 50V X7R ceramic Diodes, 1N4148-type C1, C2, C3, capacitors (0805) Fairchild MMSD4148, C7, C14, C17, 7 D1, D3 2 Murata GRM40-034X7R104K050 Vishay Liteon/Diodes, Inc. 1N4148W, C18 or Taiyo Yuden UMK212BJ104KG or General Semiconductor 1N4148W 1 F, 10V X7R ceramic capacitor Schottky diodes, 3A, 30V C4 1 Taiyo Yuden LMK212BJ105MG Nihon EC31QS03L or D2, D4 2 or Murata GRM40X7R105K10 Vishay Liteon/Diodes, Inc. B330A 1000pF, 50V X7R ceramic C5, C6, C19 3 capacitors JU1 1 2-pin header JU2 1 3-pin header 0.1 F, 50V X7R ceramic C8, C9 2 capacitors (1206) 3-pin header (MAX1757 EV kit) JU3 1 4-pin header (MAX1758 EV kit) 22 F, 35V, 0.300 , low-ESR tantalum capacitors 22 H, 2.5A inductor C10, C11 2 L1 1 AVX TPSE226M035R0300 or Sumida CDRH104R-220NC Kemet T495X226M035AS LED1, LED2 2 Light-emitting diodes (green), T1 0.22 F, 50V X7R ceramic capacitor LED3 1 Light-emitting diode (red), T1 C12 1 Taiyo Yuden UMK316BJ224ML 0.05 1%, 0.5W sense resistor R1 1 Dale WSL-2010-R050F or 4.7 F, 10V X5R ceramic capacitor IRC LRC-LR2010-01-R050-F C13 1 Taiyo Yuden LMK316BJ475ML or Murata GRM42-6X5R475K10 R2, R12 2 10k 5% resistors R3R6 0 Not installed 68 F, 20V, 0.150 , low-ESR R7, R8 2 100k 1% resistors C15 1 tantalum capacitor AVX TPSE686M020R0150 R9, R10, R11 3 1k 5% resistors R13, R14 2 4.7 5% resistors MAX1757EAI (MAX1757 EV kit) U1 1 MAX1758EAI (MAX1758 EV kit) Maxim Integrated Products 1 For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.MAX1757/MAX1758 Evaluation Kits thermistor (see Jumper Selection section). Quick Start If the charger is unable to enter the fast-charge or full- The MAX1757/MAX1758 EV kits are fully assembled charge states, charging is terminated and the fault LED and tested surface-mount boards. Follow the steps (red) lights to indicate a faulty battery. below to verify board operation. Do not turn on the power supply until all connections are completed. For more information on the operation of the MAX1757 Observe all precautions on the battery manufactur- or MAX1758, refer to the Detailed Description sections ers data sheet. Use only lithium-ion (Li+) cells with of the MAX1757 and MAX1758 data sheets. this charger: Charging Status 1) Set jumper JU3 to indicate the number of cells in the The three LEDs on the EV kit indicate the charging status: battery pack (Table 1). LED1 (FULL) indicates that the battery pack is being 2) Place a shunt on jumper JU1 to disable the tempera- charged with a constant voltage. ture monitoring functions. LED2 (FAST) indicates that the battery pack is being 3) Place a shunt across pins 12 on JU2 to enable the charged with a constant current. MAX1757 or MAX1758. LED3 (FAULT) indicates that charging terminated ab- 4) For the MAX1757, connect a +7VDC to +14VDC normally. power supply with sufficient power rating across the VIN and GND pads. Charging Current For the MAX1758, connect a +7VDC to +28VDC The voltage at the ISETOUT pin sets the charging cur- power supply with sufficient power rating across the rent to the battery. The MAX1757/MAX1758 EV kits are VIN and GND pads. shipped with ISETOUT connected to REF. This sets the 5) Connect a lithium-ion (Li+) battery pack between the charging current to the full-scale value of 1.5A. BATT+ and BATT- pads. To change the charging current to a lower value, cut 6) Turn on the power supply. the trace shorting the two pads of R3 and install resis- tors for R3 and R4. Use the equations below to calcu- 7) Verify that LEDs 1, 2, and 3 indicate the correct late the resistor values: charging status. I = (R4 / (R3 + R4)) x 1.5A CHG Detailed Description R3 = ((1.5A / I ) - 1) x R4 CHG When battery charging is initiated, the charger enters Use 100k for R4. the prequalification state. In this state, the batteries are charged at 1/10 of the programmed current limit while Input Current the charger measures the battery to determine if it can The input current limit is set by sense resistor R1 and be charged. If the battery voltage is above 2.5V per by the voltage applied to the ISETIN pin. This sets the cell, charging begins. At this time, the batteries are input current limit to 2A (100mV/50m ). The charged at a constant current (fast-charge state) or a MAX1757/MAX1758 EV kits are shipped with ISETIN constant voltage (full-charge state). The charger exits connected to REF and a 50m sense resistor. the full-charge state and enters the top-off state once the battery current drops to 10% of the fast-charge cur- To change the input current limit to a lower value, cut rent, or the fast-charge timer expires. The charger the trace shorting the two pads of R5 and install resis- remains in the top-off state for 45 minutes, after which tors for R5 and R6. Use the equations below to calcu- charging is terminated. late the resistor values: Once charging is terminated, if the battery voltage I = (R6 / (R5 + R6)) x 2A IN drops 5% from the fully charged voltage, charging R5 = ((2A / I ) - 1) x R6 IN automatically restarts. Use 100k for R6. If at any time during charging, the thermistor input To further increase the input current limit, reduce the senses a temperature below 0C or above +50C, value of sense resistor R1. charging suspends until the temperature returns to a safe level. This kit is shipped with a 10k resistor to disable the temperature monitoring function. If temper- ature monitoring is required, connect the appropriate 2 Evaluate: MAX1757/MAX1758