MAX1508 Datasheet, PDF (6/11 Pages) Maxim Integrated Products – Linear Li Battery Charger with Integrated Pass FET, Thermal Regulation, and ACOKin 3mm x 3mm TDFN

Linear Li+ Battery Charger with Integrated Pass FET,
Thermal Regulation, and ACOK in 3mm x 3mm TDFN
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. Since
the MAX1508Y and MAX1508Z do not have a prequali-
fication state, they automatically enter soft-start upon
activation.
MAX1508
IN
BATT
OUTPUT DRIVER,
V_REF
CURRENT SENSE,
AND LOGIC
ISET
VL
0.47µF
CHG
IREF
IN
VL
REF
N
V_LUVLO
IN
V_LOK
ON
V_{INOVLO INOK}
REFOK
REFOK
TEMPERATURE
SENSOR
100°C
IN
BATT
N
LOGIC
200kΩ
MAX1508 AND
MAX1508Z ONLY
GND
VI/O
ACOK
EN (EN)
( ) ARE FOR MAX1508Y ONLY
Figure 1. Functional Diagram
6 _______________________________________________________________________________________