MAX1879EUA-T Maxim Integrated Products, MAX1879EUA-T Datasheet - Page 5

• Manufacturer Part Number: MAX1879EUA-T
• Description: Battery Management 1-Cell Li+ Pulse Charger
• Manufacturer: Maxim Integrated Products

(V
IN
1.020
1.015
1.010
1.005
1.000
0.995
0.990
0.985
0.980
PIN
= CHG = +10V, V
1
2
3
4
5
6
7
8
-40
-20
vs. AMBIENT TEMPERATURE
NORMALIZED TIMER PERIOD
NORMALIZED TO +25°C
THERM
NAME
GATE
BATT
TSEL
CHG
GND
ADJ
IN
Simple, Efficient, 1-Cell Li+ Pulse Charger
TEMPERATURE (°C)
0
_______________________________________________________________________________________
BATT
20
Input Voltage from Current-Limited Voltage Source (+22V max). Bypass to GND with a 0.1µF capacitor.
Gate Drive for External PMOS Pass Element. The PMOS device should have a V
2.5V. See Selecting External Components.
Charge Status Indication. A CHG low indicates that the MAX1879 is charging a battery. CHG goes high
when the on/off duty cycle falls to 1/8, indicating that the battery is charged to approximately 95% of full
capacity. CHG is an open-drain current-limited N-channel MOSFET suitable for directly driving an LED.
Connect a pullup resistor to the logic supply to generate a logic-level signal. CHG blinks at 2Hz during the
Prequalification state (2.2V < V
Minimum ON/OFF Pulse Width Selection (Table 2)
Battery Regulation Voltage Adjustment. Bypass to GND with a 1000pF capacitor. Connect a resistor from
ADJ to GND to reduce the nominal +4.200V regulation set point. See Adjusting the Battery Regulation
Voltage.
Ground. See Layout Guidelines for information on system grounding. Connect the battery’s negative
terminal to GND.
Thermistor Temperature-Sensor Input. Connect an NTC thermistor (10kΩ at +25°C) from THERM to GND to
allow prequalification of the cell temperature for fast-charge. Replace the thermistor with a 10kΩ resistor if
temperature sensing is not required.
Cell Voltage Monitor Input, Precharge Current Output, and MAX1879 Power Source. Connect BATT to the
positive terminal of a single Li+ cell. Bypass BATT with a capacitor to ground (1.5µF per amp of charge
current).
= +4.2V, THERM = 10kΩ to GND, T
40
60
80
1.0020
1.0015
1.0010
1.0005
1.0000
0.9995
0.9990
0.9985
0.9980
0.9975
0.9970
-40
NORMALIZED BATTERY REGULATION
NORMALIZED TO +25°C
BATT
-20
VOLTAGE vs. TEMPERATURE
< 2.5V) and during a temperature fault.
A
TEMPERATURE (°C)
0
= +25°C, unless otherwise noted.)
20
Typical Operating Characteristics
FUNCTION
40
60
80
9.0
8.8
8.6
8.4
8.2
8.0
7.8
7.6
7.4
7.2
7.0
5
GS
V
PRECHARGE CURRENT
10
BATT
Pin Description
vs. INPUT VOLTAGE
threshold less than
= 0
V
V
IN
BATT
15
(V)
= 2V
20
25
5