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19-1884; Rev 0;12/00
MAX1737 Evaluation Kit
General Description
The MAX1737 evaluation kit (EV kit) is an assembled and tested PC board that implements a step-down, switching lithium-ion (Li+) battery charger. It can be set to charge 1 to 4 series cells. The cell voltage can be set between 4.0V and 4.4V, using standard 1% resistors, while maintaining 1% overall regulation accuracy. The MAX1737 detects faulty cells and terminates charging. Two capacitors are used to set the charge termination, prequalification, and fault timeout periods. Three LEDs indicate the charging status. A user-supplied thermistor can be connected to the MAX1737 EV kit to monitor battery temperature and suspend charging for over- and undertemperature conditions. o o o o o o o
Features
Complete Li+ Charging Solution for 1 to 4 Cells Low Heat and High Efficiency 300kHz PWM Operation Up to 28V Input Voltage Range 28-Pin QSOP Package Surface-Mount Construction Fully Assembled and Tested
Evaluates: MAX1737
Ordering Information
PART MAX1737EVKIT TEMP. RANGE 0C to +70C IC PACKAGE 28 QSOP
Component List
DESIGNATION QTY DESCRIPTION 4.7F, 10V X5R ceramic capacitor Taiyo Yuden LMK316BJ475ML or Murata GRM42-6X5R475K10 0.1F, 50V X7R ceramic capacitors (0805) Murata GRM40034X7R104K050 or Taiyo Yuden UMK212BJ104KG 0.22F, 50V X7R ceramic capacitor Taiyo Yuden UMK316BJ224ML 0.047F, 50V X7R ceramic capacitors 0.1F, 50V X7R ceramic capacitors (1206) 1000pF, 50V X7R ceramic capacitors 68F, 20V, 0.150, low-ESR tantalum capacitor AVX TPSE686M020R0150 22F, 35V, 0.300, low-ESR tantalum capacitors AVX TPSE226M035R0300 or Kemet T495X226M035AS Schottky diodes, 3A, 40V Fairchild MBRS340, General Semiconductor SS34, Motorola MBRS340, or Vishay Liteon/Diodes, Inc. B340 DESIGNATION QTY DESCRIPTION Diodes 1N4148-type Fairchild MMSD4148, General Semiconductor 1N4148W, or Vishay Liteon/ Diodes, Inc. 1N4148W 2-pin headers 3-pin headers 4-pin header Not installed 22H, 2.8A inductor Sumida CDRH124-220 Light-emitting diodes (green) Light-emitting diode (red) Dual N-channel MOSFET Fairchild FDS6990A 10k 5% resistors 1k 5% resistors 100k 1% resistors 0.05 1%, 0.5W sense resistor Dale-Vishay WSL-2010-R050F or IRC LRC-LR2010-01-R050-F 4.7 5% resistors Not installed 0.1 1%, 0.5W sense resistor Dale-Vishay WSL-2512-R100F or IRC LRC-LR2512-01-R100-F MAX1737EEI Shunts
C1
1
D2, D3
2
JU1, JU3, JU4 JU2, JU5 JU6 JU7, JU8 L1 LED1, LED2 LED3 N1 (N1A, N1B) R1, R11 R2, R3, R4 R5-R10
5 2 1 0 1 2 1 1 2 3 6
C2, C4, C7, C10, C11
5
C3
1
C5, C6 C8, C9 C12, C13, C14, C21, C22, C23 C15
2 2 6 1
R12
1
C18, C19
2
R13, R14, R19, R20 R15, R17 R18 U1 None
4 0 1 1 5
D1, D4
2
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX1737 Evaluation Kit Evaluates: MAX1737
Quick Start
The MAX1737 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. Use only lithium-ion cells with this charger: 1) Set jumper JU6 to indicate the number of cells in the battery pack (Table 1). 2) Place a shunt on jumper JU1 to disable the temperature monitoring function. 3) Place a shunt across pins 1-2 on JU2 to enable the MAX1737. 4) Place a shunt across JU3 to enable 2A charging current limit. 5) Place a shunt across JU4 to enable 2A input current limit. 6) Remove any shunt from JU5 to set the cell voltage to 4.2V. If a different battery regulation voltage is required, refer to the MAX1737 data sheet. 7) Connect a +7VDC to +28VDC power supply with sufficient power rating across the VIN and GND pads. 8) Connect a lithium-ion battery pack between the BATT+ and BATT- pads. 9) Turn on the power supply. 10) Measure the battery voltage and verify that the LEDs indicate the correct state. (red) lights indicate a faulty battery. This kit is shipped with a 10k resistor to disable the temperature monitoring function. If temperature monitoring is required, connect the appropriate thermistor (see Jumper Selection section). For more information on the operation of the MAX1737, refer to the Detailed Description section of the MAX1737 data sheet.
Charging Status
The three LEDs on the EV kit indicate the charging status: * LED1 (FULLCHG) indicates that the battery pack is being charged with a constant voltage. * LED2 (FASTCHG) indicates that the battery pack is being charged with a constant current. * LED3 (FAULT) indicates that charging terminated abnormally.
Jumper Selection
Jumper JU1 connects the MAX1737 thermistor input (THERM) to GND through a 10k resistor, disabling temperature qualification. To enable temperature qualification (charging between 0C and 50C), remove the shunt from JU1, and connect a thermistor (BC Components part number 2322-640-63103 or equivalent) to the THERM and GND pads. For more information, refer to the MAX1737 data sheet. The MAX1737 can be placed in shutdown mode using jumper JU2. See Table 1 for jumper settings. Jumper JU3 sets the charging current limit (current to the battery). A shunt across this jumper limits the output current to 2A. With the shunt removed, a resistor-divider formed by R5 and R6 sets the current. The EV kit comes with the resistors selected for a 1A current limit. A different current can be selected by changing the resistors (refer to the MAX1737 data sheet). Jumper JU4 sets the input current limit (current from the power supply). A shunt across this jumper limits the input current to 2A. With the shunt removed, a resistordivider formed by R7 and R8 sets the current. The EV kit comes with the resistors selected for a 1A current limit. A different current can be selected by changing the resistors (refer to the MAX1737 data sheet). Jumper JU5 sets the voltage per cell. Jumper JU6 selects the number of series cells to be charged. See Table 1 for jumper settings.
Detailed Description
When battery charging is initiated, the charger enters the prequalification state. In this state, the batteries are charged at 1/20 of the programmed current limit while the charger measures the battery to determine if it can be charged. If the battery voltage is above 2.5V per cell, charging begins. At this time, the batteries are charged at a constant current (Fast Charge state) and 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 10% of the Fast Charge current, or the Fast Charge timer expires. The charger remains in the Top Off state for 45 minutes, at which time 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 0C or above +50C, charging suspends until the temperature returns to a safe level. If the charger is unable to enter the Fast Charge or Full Charge state, charging is terminated and the Fault LED
2
_______________________________________________________________________________________
MAX1737 Evaluation Kit Evaluates: MAX1737
Table 1. Jumper Selection
JUMPER JU1 JUMPER POSITION Open Closed* 1-2* JU2 2-3 Open JU3 JU4 Open Closed* Open Closed* 1-2 JU5 2-3 Open* 1-2* JU6 1-3 1-4 Open FUNCTION Open before connecting a thermistor from THERM to GND pads. Bypasses THERM with 10k resistor. SHDN = high. MAX1737 enabled. SHDN = low. MAX1737 disabled. Drive SHDN pad with an external signal. ISETOUT = REF/2. Charging current limited to 1A. ISETOUT = REF. Charging current limited to 2A. ISETIN = REF/2. Input current limited to 1A. ISETIN = REF. Input current limited to 2A. VADJ = REF. Voltage per cell = 4.4V. VADJ = GND. Voltage per cell = 4.0V. VADJ = REF/2. Voltage per cell = 4.2V. Set by resistor-dividers R9 and R10. CELL = GND. Cell count = 1. CELL = VL. Cell count = 4. CELL = REF. Cell count = 3. CELL = Float. Cell count = 2.
*Default position
For other voltages, refer to the Setting the Battery Regulation Voltage section of the MAX1737 data sheet.
Component Suppliers
SUPPLIER AVX BC Components Dale-Vishay Fairchild General Semiconductor International Resistive Co. (IRC) Kemet Motorola Murata Sumida Taiyo Yuden Vishay Liteon/Diodes, Inc. PHONE 803-946-0690 803-772-2500 402-564-3131 408-822-2000 631-847-3000 310-322-3331 408-986-0424 303-675-2140 814-237-1431 847-956-0666 408-573-4150 805-446-4800 FAX 803-626-3123 402-563-6418 408-822-2102 631-847-3236 310-322-3332 408-986-1442 303-675-2150 814-238-0490 847-956-0702 408-573-4159 805-446-4850
_______________________________________________________________________________________
3
MAX1737 Evaluation Kit Evaluates: MAX1737
THERM
4 JU1 1 R1 10k LED1 R2 1k LED2 R3 1k LED3 R4 1k 18 15 16
D2 THM DCIN 28 C7 0.1F R13 4.7 C8 0.1F R14 4.7 C9 0.1F DH1 FASTCHG 24 LX 23 C18 22F
+
VIN D1 R12 0.05 1%
+
VL C1 4.7F C2 0.1F 17 FULLCHG
CSSP
27
JU8 JU7 (JU7, JU8 NOT INSTALLED) N1A
U1 MAX1737
CSSN
26
C19 22F
25
R15 (SHORTED BY PCB TRACE) C10 0.1F D3 C11 0.1F L1 22H
FAULT
BST
SHDN
1 2 3 R5 100k 1% JU2
SHDN
VLO
22
5 REF C3 0.22F 3 R6 100k 1% 2 ISETIN R9 100k 1% R10 100k 1% 12 R11 10k C4 0.1F C21 1000pF CELL CCV CCI 11 C5 0.047F JU4 R8 100k 1% 8 VADJ TIMER1 CS ISETOUT DLO
21 R17 (SHORTED BY PCB TRACE) N1B
D4
PGND 20 R19 4.7 C12 1000pF BATT C22 1000pF R18 0.1 1%
GND
JU3 R7 100k 1%
19
1 JU5 2 3 4 JU6 1 3 2
BATT+ 7 13 C23 1000pF C13 1000pF R20 4.7
+
C15 68F BATT-
TIMER2
14 C14 1000pF
9
CCS 10 C6 0.047F
GND 6
Figure 1. MAX1737 EV Kit Schematic
4
_______________________________________________________________________________________
MAX1737 Evaluation Kit Evaluates: MAX1737
ACTUAL BOARD SIZE IS 2.9in x 3.4in Figure 2. MAX1737 EV Kit Component Placement Guide-- Component Side
ACTUAL BOARD SIZE IS 2.9in x 3.4in Figure 3. MAX1737 EV Kit PC Board Layout--Component Side
ACTUAL BOARD SIZE IS 2.9in x 3.4in Figure 4. MAX1737 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, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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