MAX1508 Datasheet, PDF (7/11 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
V_BATT < 2.5V
PRECHARGE
10% CHARGE CURRENT
LED = ON
(MAX1508 ONLY)
VI_V^NI<E_NN>7=VVLB^AOANT_WD^{T AND}
SHUTDOWN
CHARGER = OFF
LED = OFF
ASYNCHRONOUS FROM
ANYWHERE
V_IN > 7V +
V_BATT > VIN +
EN = HIGH
V_IN > 7V +
V_BATT > V_IN +
EN = HIGH
V_BATT < 2.4V
V_BATT > 2.5V
FAST CHARGE
100% CHARGER CURRENT
LED = ON
I_CHARGE > 20%
OF ISET
I_CHARGE < 10%
OF ISET
FULL BATT
LED = OFF
FULL BATT CONTINUES
TO REGULATE BATT
UP TO 4.2V
Figure 2. Charge State Diagram
Applications Information
Charge-Current Selection
The maximum charging current is programmed by an
external R_ISET resistor connected from ISET to GND.
Select the R_ISET value based on the following formula:
I_FAST = 1461V / R_ISETΩ
where I_FAST is in amps and R_ISET is in ohms. ISET can
also be used to monitor the fast-charge current level.
The output current from the ISET pin is 0.958mA per
amp of charging current. The output voltage at ISET is
proportional to the charging current as follows:
V_ISET = (I_CHG x R_ISET) / 1044
The voltage at ISET is nominally 1.4V at the selected
fast-charge current, and falls with charging current as
the cell becomes fully charged.
Thermal Regulation
The MAX1508 features a proprietary thermal-regulation
circuit to protect both the IC and the system from
excessive heat. When the MAX1508’s die temperature
reaches +100°C, the charge current is reduced to pre-
vent any additional increase in the die temperature. An
active thermal loop does not indicate a fault condition.
Thermal regulation allows the MAX1508 to provide con-
tinuous charge to the battery under adverse conditions
without causing excessive power dissipation.
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