Datasheet

MAX8808X/MAX8808Y/MAX8808Z
1A Linear Li+ Battery Chargers with Integrated Pass
FET and Thermal Regulation in 2mm x 2mm TDFN
6 _______________________________________________________________________________________
Detailed Description
The MAX8808X/MAX8808Y/MAX8808Z chargers use
voltage, current, and thermal-control loops to charge a
single Li+ cell and protect the battery (Figure 1). When
a Li+ battery with a cell voltage below 2.5V is inserted,
the MAX8808X charger enters the prequalification
stage where it precharges that cell with 10% of the
user-programmed fast-charge current (Figure 2). The
CHG indicator output is driven low to indicate entry into
the prequalification state. When battery voltage
exceeds 2.5V, the charger soft-starts as it enters the
fast-charge stage. In the MAX8808X/MAX8808Y/
MAX8808Z, the fast-charge current level is pro-
grammed through a resistor from ISET to GND. As the
battery voltage approaches 4.2V, the charging current
is reduced. If the battery current drops to less than
10% of the fast-charging current, the CHG indicator
goes high impedance, signaling that the battery is fully
charged. The ICs then enter a constant voltage-regula-
tion mode to maintain the battery at full charge.
MAX8808X
MAX8808Y
MAX8808Z
IN
ISET
VL
I
REF
CHG
EN (MAX8808Y)
GND
BATT
1µF
ACOK
TEMP
SENSOR
OUTPUT DRIVER, CURRENT
SENSE, AND LOGIC
VL
REF OK
0.47µF
100kΩ
2.8kΩ
V
I/O
1µF
4.25V TO 15V
OVP
UVLO
LOGIC
IN
ON
V
REF
+115°C
BATT
IN
IN
REF
N
100kΩ
V
I/O
EN
(MAX8808X/
MAX8808Z)
200kΩ
Figure 1. Functional Diagram