19-2177; Rev 0; 10/01 MAX1879 Evaluation Kit Features ♦ Simple Stand-Alone Li+ Charger ♦ Low Power Dissipation ♦ Safely Precharges Over-Discharged Cells ♦ Top-Off Charging to Achieve Full Battery Capacity ♦ 8-Pin µMAX Package ♦ Surface-Mount Construction ♦ Fully Assembled and Tested Ordering Information Component Suppliers SUPPLIER PHONE FAX PART TEMP. RANGE MAX1879EVKIT 0°C to +70°C Fairchild 408-822-2000 408-822-2102 Leader Electronics 770-729-9720 770-729-9726 Murata 814-237-1431 814-238-0490 Nihon 661-867-2555 661-867-2698 Taiyo Yuden 408-573-4150 408-573-4159 Toshiba 949-455-2000 949-859-3963 IC PACKAGE 8 µMAX Note: Please indicate that you are using the MAX1879 when contacting these manufacturers. Component List DESIGNATION QTY C1, C6 0 Not installed (0805) C2, C3 2 0.1µF ±10%, 50V ceramic capacitors (0805) Taiyo Yuden UMK212BJ104KG C4 0 Not installed (0603) C5 1 2.2µF ±20%, 10V ceramic capacitor (0805) Taiyo Yuden LMK212BJ225MG C7 1 DESCRIPTION 1000pF ±10%, 50V ceramic capacitor (0603) Murata GRM188R71H102KA01 DESIGNATION QTY DESCRIPTION P1 1 20V, 4.5A, P-channel MOSFET (SuperSOT-6) Fairchild FDC638P J1 1 PC-mount power jack, 2.1mm CUISTACK CP-202A JU1 1 4-pin header JU2, JU3 2 2-pin headers U1 1 MAX1879EUA (8-pin µMAX) None 1 AC adapter: input 90-264VAC, 47-63Hz, output 6VDC/400mA Leader Electronics Inc. MI060100-30/MI3-UL or equivalent R1 1 412kΩ ±1% resistor (0805) R2 1 10kΩ ±5% resistor (0805) None 3 Shunts (JU1, JU2, JU3) 1 LED (T-13/4) None None 1 1 MAX1879 PC board MAX1879 data sheet 1 1A Schottky diode (SOT123) Nihon EP10QY03 or Toshiba CRS02 None 1 MAX1879 EV kit data sheet LED1 D1 ________________________________________________________________ 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: MAX1879 General Description The MAX1879, in conjunction with a P-channel MOSFET and a current-limited wall-mount adapter with an output voltage between +4.7V to +20V, allows safe and quick charging of a single lithium-ion (Li+) cell. The MAX1879 evaluation kit (EV kit) is a complete, fully assembled and tested Li+ battery charger. Jumpers on the EV kit allow easy adjustment to a +4.1V or +4.2V battery regulation voltage. A light-emitting diode (LED) indicates the cell’s charging status. A 6VDC, currentlimited wall-mount cube that supplies 400mA of constant current is included with the kit. Evaluates: MAX1879 MAX1879 Evaluation Kit Quick Start The MAX1879 EV kit is a fully assembled and tested surface-mount board. Follow the steps below to verify board operation. Do not plug the wall cube in until indicated. 1) Install a shunt across pins 1 and 2 of jumper JU1 (TSEL) for a minimum 34ms on-time top-off pulse width. 2) Install a shunt across jumper JU2 (THERM) to disable the temperature-monitoring function. 3) Verify that a shunt is not across jumper JU3 (ADJ) if charging a +4.2V Li+ battery. Install a shunt across jumper JU3 if charging a +4.1V Li+ battery. 4) Connect the wall cube to the power jack (J1) connector on the EV kit. 5) Place a voltmeter across the EV kit’s BATT+ and BATT- terminals. 6) Plug in the wall adapter. 7) Observe correct Li+ cell polarity. Connect a single-cell Li+ battery across the EV kit’s BATT+ and BATT- terminals. The LED will turn on if the battery voltage is below the predetermined voltage (4.1V or 4.2V) and greater than +2.5V. Refer to Table 4 for additional LED status descriptions. 8) The LED will turn off once the Li+ cell has been charged to the predetermined voltage. Detailed Description The MAX1879 EV kit is a fully assembled and tested single Li+ battery charger. The EV kit contains an external P-channel MOSFET for current switching and can deliver up to 1A of current to an Li+ battery. The input source used on the EV kit is a +6V current-limited 400mA wall cube, but the kit is not restricted to this source. Alternate current-limited power sources can be used for higher currents. The EV kit contains a jumper that sets the battery (BATT) regulation voltage to +4.1V or +4.2V. An external resistor can also adjust the regulation voltage from +4.0V to +4.2V. An LED indicates the charging status of the battery. The maximum charging time is 6.25 hours. The MAX1879 employs thermistor feedback to prequalify the Li+ cell’s temperature for fast charging. The EV kit contains a jumper that allows the user to bypass this feature or to connect an external thermistor to the EV kit board. Input Source The input source for the MAX1879 EV kit must be a current-limited supply capable of continuous short-circuit operation. The supply should have a current limit of ≤ 1A and an output voltage between +4.7V and +20V. The adapter provided with the EV kit is a +6V source 2 capable of supplying 400mA. Alternate current-limited power sources can be used for higher charge currents, but diode D1 and MOSFET P1 must be rated accordingly. Jumper Selection The MAX1879 EV kit features jumpers (JU1, JU2, and JU3) to configure the circuit for optimal charging performance and evaluation. Jumper JU1 sets the minimum on-time pulse width. Refer to Table 1 for the JU1 shunt configuration to select the appropriate top-off pulse width. Refer to the Selecting Minimum On-Time section in the MAX1879 data sheet for information on selecting the minimum ontime pulse width in top-off mode. Table 1. JU1 Shunt Positions MINIMUM ON-TIME IN TOP-OFF (ms) SHUNT POSITION TSEL PIN 1-2 Connected to BATT 34 1-3 Connected to ADJ 69 1-4 Connected to GND 137 Jumper JU2 connects the MAX1879 thermistor input (THERM) to a 10kΩ resistor, thus disabling temperature qualification. To enable temperature qualification, remove the shunt from JU2 and connect a thermistor between the THERM and GND pads. The thermistor should be 10kΩ at +25°C and have a negative temperature coefficient. See Table 2 for the JU2 configuration. Refer to the Thermistor section in the MAX1879 data sheet for other thermistor details. Table 2. Using a Thermistor JUMPER JUMPER STATE FUNCTION Open Open before connecting a thermistor from THERM pad to GND JU2 Closed Bypasses THERM with 10kΩ resistor Jumper JU3 sets the battery regulation voltage. The EV kit comes with two voltage options, 4.2V (JU3 open) and 4.1V (JU3 closed). For other voltages (+4.0V to +4.2V), replace resistor R1. Refer to the Adjusting the Battery Regulation Voltage section in the MAX1879 data sheet to select resistor R1. See Table 3 for the JU3 configuration. _______________________________________________________________________________________ MAX1879 Evaluation Kit Evaluates: MAX1879 Table 3. Fixed Voltage Regulation JUMPER JU3 JUMPER STATE Open VOLTAGE REGULATION 4.2V Closed 4.1V Output Signal The LED on the EV kit is driven by the CHG pin. Depending on the Li+ cell’s charging status, the pin is low or high impedance, thus turning the LED on or off. If a thermistor is installed, and the cell temperature is unacceptable for fast charging, or the charger is in the precharging state, the LED blinks at 2Hz. The EV kit stops charging the cell during a temperature fault. See Table 4 for LED and CHG states. For driving logic circuits, remove the LED and install a 100kΩ pullup resistor from CHG to the logic supply of the CHG monitoring circuit. A logic low signal will appear at CHG when the charger is in fast-charge; otherwise, a logic high signal will be detected. During the precharging or temperature fault state, the output logic signal will alternate between low and high at a fixed frequency of 2Hz. See Table 4. Table 4. LED States LED CONDITION CHG STATE Off No battery, no wall cube, cell voltage < 2.2V, top-off, or battery charged High impedance On Fast-charge in progress Low impedance Precharging near-dead cells (+2.2 to +2.5V) or temperature fault during fast-charge High-low impedance (50% duty cycle) Blinking (2Hz) _______________________________________________________________________________________ 3 Evaluates: MAX1879 MAX1879 Evaluation Kit BATT- GND WALL CUBE D1 1 3 J1 2 4 P1 LED1 3 1 2 BATT+ C5 2.2µF 5 6 C1 OPEN VIN 1 IN BATT 8 C2 0.1µF GATE 2 GATE THERM C4 OPEN U1 CHG THERM 7 JU2 MAX1879 3 4 CHG GND TSEL ADJ R2 10kΩ 6 5 C7 1000pF 2 JU1 1 4 3 C3 0.1µF JU3 R1 412kΩ 1% Figure 1. MAX1879 EV Kit Schematic 4 _______________________________________________________________________________________ C6 OPEN MAX1879 Evaluation Kit Figure 3. MAX1879 EV Kit PC Board Layout—Component Side Figure 4. MAX1879 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. 5 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. Evaluates: MAX1879 Figure 2. MAX1879 EV Kit Component Placement Guide— Component Side