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19-1182; Rev 2; 12/98
MAX745 Evaluation Kit
_______________General Description
The MAX745 evaluation kit (EV kit) is an assembled and tested PC board that implements a step-down, switching power supply designed for charging lithium-ion (LiIon) batteries. The output voltage can be set for one to four cells. The cell voltage can be set between 4.0V and 4.4V, with 0.75% accuracy, using standard 1% resistors. Two LEDs indicate the charging status. The MAX745 should be used to charge only Li-Ion battery packs. To charge other types of batteries, use the MAX1648 or the MAX712/MAX713. To charge SMBusTM smart-battery packs, use the MAX1647.
____________________________Features
o Charges One to Four Li-Ion Cells o Low Heat/High Efficiency o 300kHz PWM Operation o 0.75% Overall Accuracy over Temperature o 6V to 24V Input Voltage Range o Proven PC Board Layout o Fully Assembled and Tested
Evaluates: MAX745
______________Component Suppliers
SUPPLIER* AVX Dale-Vishay International Rectifier IRC Motorola Sanyo Sumida PHONE (803) 946-0690 (402) 564-3131 (310) 322-3331 (512) 992-7900 (602) 303-5454 (619) 661-6835 (847) 956-0666 FAX (803) 626-3123 (402) 563-6418 (310) 322-3332 (512) 992-3377 (602) 994-6430 (619) 661-1055 (847) 956-0702
______________Ordering Information
PART MAX745EVKIT TEMP. RANGE 0C to +70C BOARD TYPE Surface Mount
*Please indicate that you are using the MAX745 when contacting these component suppliers.
_____________________________________________________________Component List
DESCRIPTION 68F, 20V, 0.150, low-ESR tantalum capacitor AVX TPSE686M020R0150 0.1F ceramic capacitors 47nF ceramic capacitor 0.22F ceramic capacitor 4.7F, 10V, low-ESR capacitor Open R2, R15 C8, C10 C11 D1, D4, D6 D2 J3, J4 2 1 3 1 2 3 1 150F, 35V, 0.17, aluminum electrolytic capacitors Sanyo 35CV150GX 1000pF ceramic capacitor 3A, 40V, surface-mount Schottky diodes Motorola MBRS340T3 1N4148-type signal diode (SOT23) Banana jacks 3-pin headers 2-pin header ________________________________________________________________ Maxim Integrated Products 1 R3, R11, R12, R16 R4, R5, R10 R6, R7 R13 R14 U1 U2 None 2 4 0 2 1 1 1 1 1 R1 1 DESIGNATION QTY L1 LED1, LED2 M1 1 2 1 DESCRIPTION 22H, 2.8A surface-mount inductor Sumida CDRH125-220 Light-emitting diodes 2A, 30V, 0.080, logic-level, dual, N-channel FET International Rectifier IRF7303 0.100, 1% sense resistor Dale WSL-2010-R1F or IRC LR2010-01-R100F 10k, 5%, surface-mount resistors 100k, 1%, surface-mount resistors Shorted 1k, 5%, surface-mount resistors 8k, 5%, surface-mount resistor 24, 5%, surface-mount resistor Maxim MAX745EAP Maxim MAX931CSA Printed circuit board
DESIGNATION QTY C1 C2, C7, C9, C12 C3 C4 C5 C6 1
4 1 1 1 0
JU1, JU2, JU3 JU4
SMBus is a trademark of Intel Corp.
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
MAX745 Evaluation Kit Evaluates: MAX745
_________________________Quick Start
Do not turn on power until all connections are complete. Observe all precautions on the battery manufacturer's data sheet. Use only lithium-ion (Li-Ion) cells with this charger. 1) Set jumpers JU1 and JU2 to indicate the number of cells in the battery pack (Table 1). 2) Set jumper JU3 to the 2A position to enable 2A output current (Table 2). 3) Make sure that jumper JU4 is open to enable charger output. 4) Connect a DC power supply with sufficient power rating across the VIN and GND banana jacks (VIN is positive, GND is negative). DC input voltage should be between 6V and 24V. 5) Connect a Li-Ion battery pack between BATT and GND (BATT is positive, GND is negative). The battery can be connected with the charger off without causing damage, or it can be connected after power is applied. 6) Turn on the DC power supply. Fast charging begins as soon as the battery is connected and the DC power supply is on. 7) When the STATUS LED turns on, the charger is operating in current-regulating mode (fast charge). When the STATUS LED turns off, the charger is operating in voltage-regulating mode (float charge). 8) When the DONE LED turns on, the charging current has fallen below the threshold set by R13, indicating that charging is over. The charger can be shut down by closing jumper JU4.
_______________Detailed Description
Upon insertion, batteries are fast charged at a constant current. Batteries enter float charge when the total battery terminal voltage reaches the voltage limit. LED2 (STATUS) indicates that the charger is in currentregulating mode. This signal can be used to detect the transition from fast charge to float charge. LED1 (DONE) indicates that the battery current (fast charge) is below the threshold set by R13. The IBAT output pin sources a current that is proportional to the load current, and comparator U2 detects when that load current exceeds the threshold set by R13. R13 should not cause the IBAT voltage to exceed 2V under maximum load current. See the MAX745 data sheet.
Table 2. Jumper Functions
JUMPER JU1 JU1 JU2 JU2 JU3 JU3 JU3 JU4 JU4 STATE 3, 4 1, 2 2, 4 1, 3 2A Open 0A Open FUNCTION CELL1 = VL; three or four cells selected. CELL1 = GND; one or two cells selected. CELL0 = VL; two or four cells selected. CELL0 = GND; one or three cells selected. ISET = REF; output current limited to 2A. ISET is open; output current limited to 1A. ISET = GND; output current disabled. THM = REF; output enabled.
Closed THM = GND; output disabled.
Table 1. Configuring Number of Lithium-Ion Cells
NUMBER OF CELLS 1 2 3 4 VOLTAGE ADJUSTMENT RANGE 4V-4.4V 8V-8.8V 12V-13.2V 16V-17.6V JU1 POSITION 1, 2 1, 2 3, 4 3, 4 JU2 POSITION 1, 3 2, 4 1, 3 2, 4
2
_______________________________________________________________________________________
VL 7 IN+ INV+ OUT D4 GND 1 PGND DCIN D2 R4 SHORT 6 M1B 3 R1 0.1 1% L1 22H D6 7 8 M1A 1 BATTPGND PGND D1 C11 1000pF 2 BATT+ 4 DCIN C9 0.1F 1 IBAT DCIN VL BST 20 19 18 17 16 15 14 13 12 11 VL R10 SHORT R5 SHORT 2 C12 0.1F C7 0.1F 5 PGND PGND C8 150F 35V C10 150F 35V R14 24 VL 8 J4 BLACK R7 1k GND LED1 DONE VIN J3 RED
VL
IBAT 3 4 5 HYST REF V2 6
R13 8k
U2 MAX931
Figure 1. MAX745 EV Kit Schematic Diagram U1
LX DHI DLO PGND CS BATT STATUS CELLO CELL1 VL REF 3, 4 JU1 2A JU3 1A 0A R12 100k 1% JU2 1, 3 R16 100k 1% VL 2, 4 1, 2 3 4 CCV CCI THM/SHDN REF VADJ SETI GND R2 C2 10k 0.1F C3 47nF 5 6 7 C4 0.22F 8 9 10
C6 OPEN
VL
REF
MAX745
C1 68F 20V
R15 10k
C5 4.7F 10V
JU4
LED2 STATUS
R3 100k 1%
R6 1k
Evaluates: MAX745
_______________________________________________________________________________________
R11 100k 1%
MAX745 Evaluation Kit
3
MAX745 Evaluation Kit Evaluates: MAX745
1.0"
1.0"
Figure 2. MAX745 EV Kit Component Placement Guide-- Component Side
Figure 3. MAX745 EV Kit PC Board Layout--Component Side
1.0"
Figure 4. MAX745 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.
4 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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