19-2880; Rev 0; 6/03 MAX1908 Evaluation Kit Features ♦ Input Current Limiting ♦ ±0.5% Battery-Voltage Set-Point Accuracy Using Internal Reference ♦ Analog Inputs Control Charge Current and Battery-Voltage Set Point ♦ Monitor Outputs for Current Drawn from AC Input Source Charging Current AC Adapter Presence ♦ Up to 17.6V Battery-Voltage Set Point Ordering Information PART TEMP RANGE MAX1908EVKIT 0°C to +70°C IC PACKAGE 28 QFN ♦ +8V to +25V Input Voltage ♦ 3A Battery Charge Current ♦ Charges Any Battery Chemistry: Li+, NiCd, NiMH, Lead Acid, etc. ♦ Surface-Mount Construction ♦ Fully Assembled and Tested Component List DESIGNATION C1, C4 QTY 2 DESCRIPTION 22µF ±20%, 25V X5R ceramic capacitors (2220) TDK C5750X5R1E226M C2, C3 0 Not installed (2220) C5, C6 0 Not installed, E size C7, C9, C12, C18, C19, C20 6 0.1µF ±10%, 25V X7R ceramic capacitors (0603) Murata GRM188R71E104K TDK C1608X7R1E104K C8, C13, C14, C15, C17 0 Not installed (0603) C10 1 4.7µF ±10%, 6.3V X5R ceramic capacitor (0603) TDK C1608X5R0J475K 2 1µF ±10%, 6.3V X5R ceramic capacitors (0603) Murata GRM188R60J105K Taiyo Yuden JMK107BJ105KA TDK C1608X5R1A105K C11, C23 DESIGNATION QTY DESCRIPTION 1 1µF ±10%, 25V X7R ceramic capacitor (1206) Murata GRM31MR71E105K Taiyo Yuden TMK316BJ105KL TDK C3216X7R1E105K C21, C22 2 0.01µF ±10%, 50V X7R ceramic capacitors (0603) Murata GRM188R71H103K Taiyo Yuden UMK107B103KZ TDK C1608X7R1H103K D1 1 Schottky diode, 10A, D-Pak Diodes Inc. MBRD1035CTL ON Semiconductor MBRD1035CTL 2 Schottky diodes, 0.5A, 30V SOD-123 Diodes Inc. B0530W General Semiconductor MBR0530 ON Semiconductor MBR0530 1 Schottky diode, 1A, 40V, SMA Central Semiconductor CMSH1-40ML Diodes Inc. B130L C16 D2, D3 D4 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX1908 General Description The MAX1908 evaluation kit (EV kit) is an accurate and efficient multichemistry battery charger. It uses analog inputs to control charge voltage and current. The EV kit can charge 2 to 4 series lithium-ion (Li+) cells with a current up to 3A. High efficiency is achieved by a buck topology with synchronous rectification. The EV kit provides outputs that can be used to monitor the input current, the battery-charging current, and the presence of an AC adapter. Evaluates: MAX1908 MAX1908 Evaluation Kit Component List (continued) DESIGNATION QTY J1 1 DESCRIPTION Smart battery header assembly, right angle, keyless, 5-position Tyco Electronics 787441-1 JU1 1 2-pin header JU2, JU3, JU5, JU6 4 3-pin headers JU4 0 Not installed L1 1 10µH, 4.4A inductor Sumida CDRH104R-100NC TOKO 919AS-100M N1 1 Dual, N-channel, 8-pin SO, MOSFET Fairchild FDS6912A P1 0 Not installed 1 0.01Ω ±1%, 0.5W sense resistor (2010) Vishay Dale WSL2010 0.010 1.0% IRC LRC-LR2010-01-R010-F R2 1 0.015Ω ±1%, 0.5W sense resistor (2010) Vishay Dale WSL2010 0.015 1.0% IRC LRC-LR2010-01-R015-F R3–R6, R14, R15, R17–R20, R22, R23, R24 0 Not installed (0603) R7 1 590kΩ ±1% resistor (0603) R8 1 196kΩ ±1% resistor (0603) R9 1 4.7kΩ ±5% resistor (0603) R10, R11 2 10kΩ ±5% resistors (0603) R12, R13 2 50kΩ potentiometers (multiturn) R16 1 33Ω ±5% resistor (0603) R21 1 1MΩ ±5% resistor (0603) R25 1 10Ω ±5% resistor (0603) U1 1 MAX1908ETI (28-pin QFN-EP) R1 Quick Start Required Equipment Before beginning, the following equipment is required: • DC source to supply the input current to the charger. This source must be capable of supplying a voltage greater than the battery-voltage set point and have a sufficient current rating. 2 • DC source capable of supplying a voltage between +2.5V to +3.6V for REFIN. • Voltmeter. • Battery pack or load. Procedure The MAX1908 EV kit is a fully assembled and tested surface-mount board. 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: 1) Install a shunt on JU1 to set the battery-voltage set point to 4.2V per cell. If a different battery-voltage set point is required, see the Battery-Voltage Set Point section. 2) Place a shunt across pins 1-2 on JU2 to enable 3A charging-current limit. If the battery is not rated for 3A charge current, then select a charge current and set as explained in the Charging-Current Limit (Potentiometer R12) section. 3) Set jumper JU5 to indicate the number of cells in the battery pack (Table 1). 4) Place a shunt across pins 2-3 on JU6. 5) Place a shunt across pins 2-3 on JU3 to disable the MAX1908. 6) Connect the input-current supply across the ADAPTER_IN and PGND pads. 7) Connect the +2.5VDC to +3.6VDC power supply to REFIN and GND. 8) Connect a battery pack between the BATT+ and BATT- pads. 9) Turn on the power supplies. 10) Enable the MAX1908 by moving the shunt on JU3 to the 1-2 position. 11) Verify current is being delivered to the battery. Detailed Description The MAX1908 includes all the functions necessary to charge Li+ batteries. The EV kit is shipped with a charging-current limit of 3A and a battery-voltage set point of 4.2V times the number of cells in the battery pack. The MAX1908 safely conditions overdischarged cells by charging the battery pack at 300mA (1/10 of the charging-current limit) until the battery-pack voltage exceeds 3.1V times the number of cells. Once conditioning is complete, the MAX1908 charges the battery pack at a constant current of 3A (the charging-current limit) until the battery pack voltage reaches 4.2V times the number of cells (the battery-voltage set point). At _______________________________________________________________________________________ MAX1908 Evaluation Kit Jumper JU1 Jumper JU1 connects VCTL to LDO. This sets the battery-voltage set point to 4.2V x the number of cells. The battery-voltage set point can be set between 4.0V and 4.4V (times the number of cells) by removing the shunt on JU1 and installing resistors at R5 and R6. See the Battery-Voltage Set Point section for more information. Jumper JU2 Jumper JU2 connects ICTL to either LDO or potentiometer R12. Connecting ICTL to LDO sets the charging-current limit to 3A. Connecting ICTL to potentiometer R12 provides adjustment of the charging-current limit to between 0.156A and 5A. Refer to the Setting the Charging-Current Limit section of the MAX1908 data sheet for more information. Note: Applying a voltage less than REFIN/32 to ICTL places the MAX1908 in shutdown mode; 5A charging current requires a different inductor. The 8-pin SO dual MOSFET (N1) is capable of handling 5A at room temperature only. For a higher ambient temperature, replace it with two single 8-pin SO MOSFETs. Jumper JU3 Jumper JU3 either enables the MAX1908 or places it into shutdown. See Table 1 for jumper settings. Jumper JU4 Jumper JU4 is factory reserved. Jumper JU5 Jumper JU5 selects the number of series cells to be charged. See Table 1 for jumper settings. Jumper JU6 Jumper JU6 connects ACOK to either a 1MΩ pullup resistor or to an optional MOSFET circuit (P1, R22, and R23). Using a MOSFET provides a lower dropout voltage than Schottky diode D1. Use a P-channel MOSFET such as Fairchild FDS6675 for P1. Choose resistor values for R22 and R23 that ensure VGS is not exceeded on the MOSFET. Battery-Voltage Set Point The default battery-voltage set point on the MAX1908 EV kit is 4.2V times the number of cells. To set it to a value between 4.0V and 4.4V (times the number of cells), remove the shunt on JU1 and install resistors at R5 and R6. Use the following equation to calculate the resistor values: 0.4 R5 = R6 − 1 VBATT −4 CELLS V BATT is the desired battery-voltage set point and CELLS is the number of cells selected by jumper JU5. Choose 1% resistors with a total resistance less than 250kΩ to minimize error caused by bias current. For VBATT / CELLS = 4, use 100kΩ for R6 and leave R5 uninstalled. Charging-Current Limit (Potentiometer R12) The default charging-current limit on the MAX1908 EV kit is 3A. To set it to a value between 0.156A and 5A, move the shunt on jumper JU2 to the 2-3 position and adjust potentiometer R12. Refer to the Setting the Charging-Current Limit section of the MAX1908 data sheet for more information. Note: Five-amp charging current requires a different inductor. The 8-pin SO dual MOSFET (N1) is capable of handling 5A at room temperature only. For a higher ambient temperature, replace it with two single 8-pin SO MOSFETs. Source-Current Limit (Potentiometer R13) Potentiometer R13 is connected to CLS, the sourcecurrent-limit input. Adjusting R13 allows the input-current limit to be set between 3.75A and 7.5A. Refer to the Setting the Input-Current Limit section of the MAX1908 data sheet for more information. Evaluating the MAX1908 Above 25V To evaluate the MAX1908 with an input voltage greater than 25V (up to 28V), capacitors C1, C7, C9, and C16 must be replaced with higher voltage rating parts. Any capacitors that were installed in locations C2, C5, and C6 must also meet the higher voltage rating. _______________________________________________________________________________________ 3 Evaluates: MAX1908 this time, the MAX1908 charges the battery pack with a constant voltage equal to the battery-voltage set point. Note: During charging, if the source-current limit is reached, the charge current decreases. For more information on the operation of the MAX1908, refer to the Detailed Description section of the MAX1908 data sheet. Evaluates: MAX1908 MAX1908 Evaluation Kit Table 1. Jumper Selection JUMPER POSITION JUMPER Open JU1 Closed* Battery-voltage set point can be set between 4.0V and 4.4V times the number of cells. Resistors R5 and R6 must be installed. VCTL = LDO. Battery-voltage set point set to 4.2V times the number of cells. 1-2* ICTL = LDO. Charging-current limit set to 3A. 2-3 ICTL connected to potentiometer R12. Charging-current limit can be adjusted between 0.156A (VICTL = REFIN/32) and 5A (VICTL = REFIN). Note: VICTL < REFIN/32 places the MAX1908 in shutdown. 1-2* SHDN = high. MAX1908 enabled. 2-3 SHDN = low. MAX1908 disabled. JU2 JU3 JU4 FUNCTION Open Drive pad SHDN with an external signal. Open Factory reserved. Closed* (shorted by PC board trace) Normal operation. JU5 1-2 CELL = REFIN, cell count = 4. 2-3* CELL = GND, cell count = 2. Open JU6 CELL = float, cell count = 3. 1-2 ACOK connected to optional MOSFET circuit (P1, R22, and R23). 2-3* ACOK connected to 1MΩ pullup resistor. *Default position. Component Suppliers PHONE FAX WEBSITE Central Semiconductor SUPPLIER 631-435-1110 631-435-1824 www.centralsemi.com Diodes Inc. 805-446-4800 805-381-3899 www.diodes.com Fairchild Semiconductor 888-522-5372 — www.fairchildsemi.com General Semiconductor 760-804-9258 760-804-9259 www.gensemi.com International Resistive Co. (IRC) 361-992-7900 361-992-3377 www.irctt.com Murata 770-436-1300 770-436-3030 www.murata.com ON Semiconductor 602-244-6600 602-244-4545 www.onsemi.com Sumida 847-545-6700 847-545-6720 www.sumida.com Taiyo Yuden 800-348-2496 847-925-0899 www.t-yuden.com TDK 847-803-6100 847-390-4405 www.component.tdk.com TOKO 847-297-0070 847-699-1194 www.tokoam.com Vishay Dale 402-564-3131 402-563-6296 www.vishay.com Note: Please indicate you are using the MAX1908 when contacting these manufacturers. 4 _______________________________________________________________________________________ R8 196kΩ 1% C5 OPEN ACIN R11 10kΩ R10 10kΩ C21 0.01µF C20 0.1µF IINP ICHG JU3 5 6 7 28 9 8 11 10 13 15 12 1 CCS CCI CCV IINP ICHG SHDN ACOK ACIN ICTL VCTL REFIN REF 4 3 BST 25 22 24 2 17 19 20 21 R13 50kΩ 1 GND BATT 14 16 CSIN 18 CSIP PGND DLO C15 OPEN C13 OPEN CELLS C12 0.1µF C11 1µF CLS C3 OPEN C14 OPEN 2 7 BST R17 SHORT (PC TRACE) R25 10Ω LDO R16 33Ω C10 4.7µF JU5 R18 SHORT TP4 (PC TRACE) TP2 2 3 1 C2 OPEN REVBLK_D REFIN JU4 CUT HERE LX 23 DHI DLOV CLS 3 2 MAX1908 LDO CELLS CSSN DCIN 26 C9 0.1µF CSSP U1 R15 SHORT (PC TRACE) C8 OPEN R1 0.01Ω 27 R14 SHORT (PC TRACE) C7 0.1µF C23 1µF ACIN R24 SHORT (PC TRACE) C22 0.01µF R9 4.7kΩ C19 0.1µF C18 0.1µF 3 2 TP1 REFIN 1 ACOK C17 OPEN C16 1µF R6 OPEN D2 R22 OPEN ADPPWR_D R5 OPEN JU1 SHDN R4 OPEN R3 OPEN LDO R23 OPEN GND 2 JU2 JU6 3 2 1 ACOK P1 OPEN ACOK 3 1 LDO R12 50kΩ R21 1MΩ LDO 4 PGND REFIN R7 590kΩ 1% C6 OPEN 6 5 7 8 1 3 2 ADAPTER_IN D1 TP3 R20 SHORT (PC TRACE) R19 SHORT (PC TRACE) N1–A 1 8 D3 C4 22µF BST C1 22µF D4 5 4 N1–B 3 6 BATT+ BATT- BATT- BATT+ R2 0.015Ω L1 10µH SCL SDA THM REVBLK_S LOAD SMART BATTERY CONNECTOR J1–5 J1–10 J1–4 J1–9 J1–3 J1–8 J1–2 J1–7 J1–1 J1–6 Evaluates: MAX1908 ADPPWR_S MAX1908 Evaluation Kit Figure 1. MAX1908 EV Kit Schematic _______________________________________________________________________________________ 5 Evaluates: MAX1908 MAX1908 Evaluation Kit Figure 2. MAX1908 EV Kit Component Placement Guide— Component Side Figure 3. MAX1908 EV Kit PC Board Layout—Component Side Figure 4. MAX1908 EV Kit PC Board Layout—Signal and Ground Layer Figure 5. MAX1908 EV Kit PC Board Layout—Ground Layer 6 _______________________________________________________________________________________ MAX1908 Evaluation Kit Evaluates: MAX1908 Figure 6. MAX1908 EV Kit PC Board Layout—Solder Side Figure 7. MAX1908 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. 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