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19-2177; Rev 0; 10/01
MAX1879 Evaluation Kit
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. o Simple Stand-Alone Li+ Charger o Low Power Dissipation o Safely Precharges Over-Discharged Cells o Top-Off Charging to Achieve Full Battery Capacity o 8-Pin MAX Package o Surface-Mount Construction o Fully Assembled and Tested
Features
Evaluates: MAX1879
Component Suppliers
SUPPLIER Fairchild Leader Electronics Murata Nihon Taiyo Yuden Toshiba PHONE 408-822-2000 770-729-9720 814-237-1431 661-867-2555 408-573-4150 949-455-2000 FAX 408-822-2102 770-729-9726 814-238-0490 661-867-2698 408-573-4159 949-859-3963 PART MAX1879EVKIT
Ordering Information
TEMP. RANGE 0C to +70C IC PACKAGE 8 MAX
Note: Please indicate that you are using the MAX1879 when contacting these manufacturers.
Component List
DESIGNATION C1, C6 C2, C3 C4 C5 QTY 0 2 0 1 DESCRIPTION Not installed (0805) 0.1F 10%, 50V ceramic capacitors (0805) Taiyo Yuden UMK212BJ104KG Not installed (0603) 2.2F 20%, 10V ceramic capacitor (0805) Taiyo Yuden LMK212BJ225MG 1000pF 10%, 50V ceramic capacitor (0603) Murata GRM188R71H102KA01 412k 1% resistor (0805) 10k 5% resistor (0805) LED (T-13/4) 1A Schottky diode (SOT123) Nihon EP10QY03 or Toshiba CRS02 None None None None 3 1 1 1 P1 1 DESIGNATION QTY DESCRIPTION 20V, 4.5A, P-channel MOSFET (SuperSOT-6) Fairchild FDC638P PC-mount power jack, 2.1mm CUISTACK CP-202A 4-pin header 2-pin headers MAX1879EUA (8-pin MAX) AC adapter: input 90-264VAC, 47-63Hz, output 6VDC/400mA Leader Electronics Inc. MI060100-30/MI3-UL or equivalent Shunts (JU1, JU2, JU3) MAX1879 PC board MAX1879 data sheet MAX1879 EV kit data sheet
J1 JU1 JU2, JU3 U1
1 1 2 1
C7 R1 R2 LED1 D1
1 1 1 1 1
None
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________________________________________________________________ Maxim Integrated Products
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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.
MAX1879 Evaluation Kit Evaluates: MAX1879
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. 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
SHUNT POSITION 1-2 1-3 1-4 TSEL PIN Connected to BATT Connected to ADJ Connected to GND MINIMUM ON-TIME IN TOP-OFF (ms) 34 69 137
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.
Jumper JU2 connects the MAX1879 thermistor input (THERM) to a 10k 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 10k at +25C 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 Open JU2 Closed FUNCTION Open before connecting a thermistor from THERM pad to GND Bypasses THERM with 10k resistor
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
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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.
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MAX1879 Evaluation Kit Evaluates: MAX1879
Table 3. Fixed Voltage Regulation
JUMPER JU3 JUMPER STATE Open Closed VOLTAGE REGULATION 4.2V 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 100k 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 Off CONDITION No battery, no wall cube, cell voltage < 2.2V, top-off, or battery charged Fast-charge in progress Precharging near-dead cells (+2.2 to +2.5V) or temperature fault during fast-charge CHG STATE High impedance
On
Low impedance High-low impedance (50% duty cycle)
Blinking (2Hz)
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MAX1879 Evaluation Kit Evaluates: MAX1879
GND
BATT-
WALL CUBE
D1
4 P1 LED1 3 C1 OPEN
1 2 C5 2.2F
BATT+ C6 OPEN
1 3 J1 2 VIN
5 6
1 C2 0.1F
IN
BATT
8
GATE
2
GATE U1
THERM
7 C4 OPEN 6
THERM
JU2 R2 10k
CHG
MAX1879
3 CHG GND
4
TSEL
ADJ
5 C7 1000pF
2 JU1 1 4 3 JU3 R1 412k 1% C3 0.1F
Figure 1. MAX1879 EV Kit Schematic
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MAX1879 Evaluation Kit Evaluates: MAX1879
Figure 2. MAX1879 EV Kit Component Placement Guide-- Component Side
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 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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