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19-1816; Rev 0; 10/00
MAX1757/MAX1758 Evaluation Kits
General Description
The MAX1757/MAX1758 evaluation kits (EV kits) are assembled and tested PC boards that implement a step-down, switching lithium-ion (Li+) battery charger. The MAX1757 EV kit can be set to charge 1- to 3-series cells, and the MAX1758 EV kit can be set to charge 1to 4-series cells. The cell voltage can be set between 4.0V and 4.4V using standard 1% resistors while maintaining 1% overall regulation voltage accuracy. Three LEDs indicate the charging status. The MAX1757/MAX1758 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.
Features
o Complete Li+ Charging Solution up to 3-Series Cells (MAX1757) and 4-Series Cells (MAX1758) o 1.5A Battery-Charging Current o Low Heat/High Efficiency o 300kHz PWM Operation o o o o Up to 14V Input Voltage Range (MAX1757) Up to 28V Input Voltage Range (MAX1758) 28-Pin SSOP Package Surface-Mount Construction
Evaluate: MAX1757/MAX1758
o Fully Assembled and Tested
Ordering Information
PART MAX1757EVKIT MAX1758EVKIT IC PACKAGE 28 SSOP 28 SSOP
Component List
DESIGNATION QTY C1, C2, C3, C7, C14, C17, C18 DESCRIPTION 0.1F, 50V X7R ceramic capacitors (0805) Murata GRM40-034X7R104K050 or Taiyo Yuden UMK212BJ104KG 1F, 10V X7R ceramic capacitor Taiyo Yuden LMK212BJ105MG or Murata GRM40X7R105K10 1000pF, 50V X7R ceramic capacitors 0.1F, 50V X7R ceramic capacitors (1206) 22F, 35V, 0.300, low-ESR tantalum capacitors AVX TPSE226M035R0300 or Kemet T495X226M035AS 0.22F, 50V X7R ceramic capacitor Taiyo Yuden UMK316BJ224ML 4.7F, 10V X5R ceramic capacitor Taiyo Yuden LMK316BJ475ML or Murata GRM42-6X5R475K10 68F, 20V, 0.150, low-ESR tantalum capacitor AVX TPSE686M020R0150 DESIGNATION QTY DESCRIPTION Diodes, 1N4148-type Fairchild MMSD4148, Vishay Liteon/Diodes, Inc. 1N4148W, or General Semiconductor 1N4148W Schottky diodes, 3A, 30V Nihon EC31QS03L or Vishay Liteon/Diodes, Inc. B330A 2-pin header 3-pin header 3-pin header (MAX1757 EV kit) 4-pin header (MAX1758 EV kit) 22H, 2.5A inductor Sumida CDRH104R-220NC Light-emitting diodes (green), T1 Light-emitting diode (red), T1 0.05 1%, 0.5W sense resistor Dale WSL-2010-R050F or IRC LRC-LR2010-01-R050-F 10k 5% resistors Not installed 100k 1% resistors 1k 5% resistors 4.7 5% resistors MAX1757EAI (MAX1757 EV kit) MAX1758EAI (MAX1758 EV kit)
7
D1, D3
2
C4
1
D2, D4
2
C5, C6, C19 C8, C9
3 2
JU1 JU2 JU3 L1 LED1, LED2 LED3 R1 R2, R12 R3-R6 R7, R8 R9, R10, R11 R13, R14 U1
1 1 1 1 2 1 1 2 0 2 3 2 1
C10, C11
2
C12
1
C13
1
C15
1
________________________________________________________________ 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.
MAX1757/MAX1758 Evaluation Kits Evaluate: MAX1757/MAX1758
Quick Start
The MAX1757/MAX1758 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: 1) Set jumper JU3 to indicate the number of cells in the battery pack (Table 1). 2) Place a shunt on jumper JU1 to disable the temperature monitoring functions. 3) Place a shunt across pins 1-2 on JU2 to enable the MAX1757 or MAX1758. 4) For the MAX1757, connect a +7VDC to +14VDC power supply with sufficient power rating across the VIN and GND pads. For the MAX1758, connect a +7VDC to +28VDC 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 1, 2, and 3 indicate the correct charging status. 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 MAX1757 or MAX1758, refer to the Detailed Description sections of the MAX1757 and MAX1758 data sheets.
Charging Status
The three LEDs on the EV kit indicate the charging status: o LED1 (FULL) indicates that the battery pack is being charged with a constant voltage. o LED2 (FAST) indicates that the battery pack is being charged with a constant current. o LED3 (FAULT) indicates that charging terminated abnormally.
Charging Current
The voltage at the ISETOUT pin sets the charging current to the battery. The MAX1757/MAX1758 EV kits are shipped with ISETOUT connected to REF. This sets the charging current to the full-scale value of 1.5A. To change the charging current to a lower value, cut the trace shorting the two pads of R3 and install resistors for R3 and R4. Use the equations below to calculate the resistor values: ICHG = (R4 / (R3 + R4)) x 1.5A R3 = ((1.5A / ICHG) - 1) x R4 Use 100k for R4.
Detailed Description
When battery charging is initiated, the charger enters the prequalification state. In this state, the batteries are charged at 1/10 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) 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 10% 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 0C or above +50C, 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 temperature monitoring is required, connect the appropriate
2
Input Current
The input current limit is set by sense resistor R1 and by the voltage applied to the ISETIN pin. This sets the input current limit to 2A (100mV/50m). The MAX1757/MAX1758 EV kits are shipped with ISETIN connected to REF and a 50m 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: IIN = (R6 / (R5 + R6)) x 2A R5 = ((2A / IIN) - 1) x R6 Use 100k for R6. To further increase the input current limit, reduce the value of sense resistor R1.
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MAX1757/MAX1758 Evaluation Kits
Table 1. Jumper Selection
SUPPLIER JUMPER JUMPER POSITION FUNCTION Open before connecting a thermistor from THERM to GND pads. Bypasses THERM with a 10k resistor. SHDN = high. MAX1757/MAX1758 enabled. SHDN = low. MAX1757/MAX1758 disabled. Drive SHDN pad with an external signal. CELL = GND. Cell count = 1. CELL = VL. Cell count = 4. (MAX1758 only) CELL = REF. Cell count = 3. CELL = Float. Cell count = 2. AVX BC Components Dale-Vishay Fairchild General Semiconductor International Resistive Co. (IRC) Kemet Murata Nihon Sumida Taiyo Yuden Vishay Liteon/Diodes, Inc.
Component Suppliers
PHONE 803-946-0690 803-772-2500 402-564-3131 408-822-2000 631-847-3000 310-322-3331 408-986-0424 814-237-1431 661-867-2555 847-956-0666 408-573-4150 805-446-4800 402-563-6418 408-822-2102 631-847-3236 310-322-3332 408-986-1442 814-238-0490 661-867-2698 847-956-0702 408-573-4159 805-446-4850 FAX 803-626-3123
Evaluate: MAX1757/MAX1758
Open JU1 Closed*
1-2*
JU2
2-3
Open
Note: Please indicate that you are using the MAX1757 or MAX1758 when contacting these manufacturers.
1-2*
1-3 JU3 1-4 Open
*Default position
Jumper Selection
Jumper JU1 connects the 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 # 2322-640-63103 or equivalent) to the THERM and GND pads. For more information, refer to the MAX1757 and MAX1758 data sheets.
The EV kits can be placed in shutdown mode using jumper JU2. (See Table 1 for jumper settings.) Jumper JU3 selects the number of series cells to be charged. (See Table 1 for jumper settings.)
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3
Evaluate: MAX1757/MAX1758
4 THM DCIN JU1 D2 24 C1 0.1F CSSP C8 0.1F R14 4.7 C9 0.1F 9 HSD 10 19 20 C14 0.1F BST D3 VL VL 2 ISETIN 18 R6 OPEN PGND 7 VADJ 21 CS C17 0.1F 11 CELL BATT 8 C18 0.1F VL FULLCHG 12 TIMER1 FASTCHG 13 C6 1000pF 15 C5 1000pF 16 R9 1k LED1
+ + +
MAX1757/MAX1758 Evaluation Kits
Figure 1. MAX1757/MAX1758 EV Kit Schematic
28 VIN R13 4.7 R1 0.05 1% C7 0.1F CCI 27 D1 23 C2 0.1F R2 10k 25 C19 1000pF HSD LX 5 C4 1F 3 ISETOUT R4 OPEN 1 C13 4.7F GND 22 D4 REF R3 (SHORTED BY PCB TRACE) LX L1 22H CCV C10 22F 35V C11 22F 35V C12 0.22F C3 0.1F CCS CSSN
4
U1 MAX1757 MAX1758
26 SYSTEM LOAD R5 (SHORTED BY PCB TRACE) R7 100k 1% VL
THERM
R12 10k
*
3 1 2 JU2 SHDN 17 2 3 1 JU3
4
R8 100k 1%
BATT+ C15 68F BATT-
SHDN
_______________________________________________________________________________________
R10 1k LED2 TIMER2 FAULT GND 6 14 R11 1k LED3
*MAX1758 ONLY
MAX1757/MAX1758 Evaluation Kits Evaluate: MAX1757/MAX1758
1.0"
1.0"
Figure 2. MAX1757/MAX1758 EV Kit Component Placement Guide--Component Side
Figure 3. MAX1757/MAX1758 EV Kit PC Board Layout-- Component Side
1.0"
Figure 4. MAX1757/MAX1758 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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