19-2177; Rev 1; 9/05 MAX1879 Evaluation Kit 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. 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 PHONE FAX PART TEMP RANGE Fairchild 408-822-2000 408-822-2102 MAX1879EVKIT 0°C to +70°C Murata 814-237-1431 814-238-0490 SUPPLIER Nihon 661-867-2555 661-867-2698 Taiyo Yuden 408-573-4150 408-573-4159 Toshiba 949-455-2000 949-859-3963 Note: Indicate that you are using the MAX1879 when contacting these manufacturers. IC PACKAGE 8 µMAX µMAX is a registered trademark of Maxim Integrated Products, Inc. Component List DESIGNATION C1, C6 C2, C3 C4 C5 C7 D1 QTY DESCRIPTION 0 Not installed (0805) 2 0.1µF ±10%, 50V ceramic capacitors (0805) Taiyo Yuden UMK212BJ104KG 0 Not installed (0603) 1 2.2µF ±20%, 10V ceramic capacitor (0805) Taiyo Yuden LMK212BJ225MG 1 1000pF ±10%, 50V ceramic capacitor (0603) Murata GRM188R71H102KA01 1 1A Schottky diode (SOT123) Nihon EP10QY03 or Toshiba CRS02 DESIGNATION QTY DESCRIPTION LED1 1 LED (T-13/4) J1 1 PC-mount power jack, 2.1mm JU1 1 4-pin header JU2, JU3 2 2-pin headers P1 1 20V, 4.5A, p-channel MOSFET (6-pin SuperSOT) Fairchild FDC638P R1 1 412kΩ ±1% resistor (0805) R2 1 10kΩ ±5% resistor (0805) U1 1 MAX1879EUA (8-pin µMAX) — 3 Shunts (JU1, JU2, JU3) — 1 MAX1879 PC board ________________________________________________________________ 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 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 a 6V current-limiting (≤ 1A) power supply across the EV kit’s WALL CUBE and GND terminals. 5) Place a voltmeter across the EV kit’s BATT+ and BATT- terminals. 6) Observe correct Li+ cell polarity. Connect a single-cell Li+ battery across the EV kit’s BATT+ and BATT- terminals. The LED turns on if the battery voltage is below the predetermined voltage (4.1V or 4.2V) and greater than +2.5V. See Table 4 for additional LED status descriptions. 7) The LED turns 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 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. Connect a current-limited wall cube to power jack J1 (center pin is the positive terminal); otherwise, connect a current-limited power-supply across the WALL CUBE and GND PC pads. Current-limited power sources with higher charge currents can be used, but diode D1 and MOSFET P1 must be rated accordingly. 2 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. See 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 on-time pulse width in top-off mode. Table 1. JU1 Shunt Positions SHUNT POSITION TSEL PIN MINIMUM ON-TIME IN TOP-OFF (ms) 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 JUMPER JU3 JUMPER STATE Open Closed VOLTAGE REGULATION 4.2V 4.1V 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) 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. Blinking (2Hz) 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 appears at CHG when the charger is in fast-charge; otherwise, a logic high signal is detected. During the precharging or temperature fault state, the output logic signal alternates between low and high at a fixed frequency of 2Hz. See Table 4. _______________________________________________________________________________________ 3 Evaluates: MAX1879 Table 3. Fixed Voltage Regulation 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. Evaluates: MAX1879 Figure 2. MAX1879 EV Kit Component Placement Guide— Component Side