Datasheet

DC Input Sources
The MAX8808X/MAX8808Y/MAX8808Z operate from
well-regulated DC sources. The full charging input volt-
age range is 4.25V to 7V. The device can withstand up
to 15V on the input without damage to the IC. If V
IN
is
greater than 7V, the internal overvoltage-protection cir-
cuitry disables charging until the input falls below 7V.
An appropriate power supply must provide at least
4.25V at the desired peak charging current. It also must
stay below 6.5V when unloaded.
Application Circuits
Stand-Alone Li+ Charger
The MAX8808X/MAX8808Y/MAX8808Z provide a com-
plete Li+ charging solution. Figure 3 shows a stand-
alone Li+ battery charger. The 2.8kΩ resistor
connected to ISET sets a charging current of 465mA.
The LED connected to the CHG output indicates when
either fast-charge or precharge qualification has
begun. When the battery is full, CHG turns high imped-
ance and the LED turns off.
Microprocessor-Interfaced Charger
Figure 4 shows the MAX8808X as a µP co-operated Li+
battery charger. The MAX8808X begins charging the bat-
tery when EN is low. The µP can drive EN high to disable
the charger. The MAX8808X generates a ACOK signal to
indicate the presence of an input supply. CHG is used to
detect the charge status of the battery. By monitoring
V
ISET
, the system can measure the charging current.
MAX8808X/MAX8808Y/MAX8808Z
1A Linear Li+ Battery Chargers with Integrated Pass
FET and Thermal Regulation in 2mm x 2mm TDFN
_______________________________________________________________________________________ 9
MAX8808X
(MAX8808Y)
MAX8808Z
IN
4.2V
Li+
R3
100kΩ
AC-INPUT
PRESENT
INDICATOR
R2
510Ω
C2
1µF
C3
0.47µF
C1
1µF
4.25V TO 15V
V
I/O
ISET VL
GND
EN (EN)
CHG
R1
2.8kΩ
ENABLE
INPUT
BATT
ACOK
Figure 3. Stand-Alone Li+ Battery Charger
MAX8808XETA
IN
4.2V
Li+
C2
1µF
C1
1µF
AC/DC
ADAPTER
ISET
EN
CHG
SYSTEM
VL
BATT
R1
2.8kΩ
GND
C3
0.47µF
R4
100kΩ
V
I/O
V
I/O
ACOK
R3
100kΩ
R2
10kΩ
CHARGE-CURRENT MONITOR
LOW: CHARGE, HIGH: FULL OR OFF
C4
0.1µF
Figure 4. µP-Interfaced Li+ Battery Charger