Manual

MAX1508
Linear Li+ Battery Charger with Integrated Pass FET,
Thermal Regulation, and
ACOK in 3mm x 3mm TDFN
6 _______________________________________________________________________________________
MAX1508
OUTPUT DRIVER,
CURRENT SENSE,
AND LOGIC
V
LUVLO
V
INOVLO
IN
ON
INOK
REFOK
V
LOK
REFOK
REF
VL
N
LOGIC
TEMPERATURE
SENSOR
V
REF
IREF
IN
ISET
VL
0.47µF
BATT
EN
200kΩ
GND
IN
100°C
BATT
CHG
IN
N
ACOK
VI/O
CHG Charge Indicator Output
CHG is an open-drain current source for indicating
charge status. Table 1 describes the state of CHG dur-
ing different stages of operation.
CHG is a nominal 12mA current source suitable for dri-
ving a charge-indication LED. If the MAX1508 is used
in conjunction with a microprocessor, a pullup resistor
to the logic I/O voltage allows CHG to indicate charge
status to the µP instead of driving an LED.
Soft-Start
An analog soft-start algorithm activates when entering
fast-charge mode. When the prequalification state is
complete (V
BATT
exceeds +2.5V), the charging current
ramps up in 3ms to the full charging current. This
reduces the inrush current on the input supply.
Figure 1. Functional Diagram