MAX1508 Maxim, MAX1508 Datasheet - Page 7

• Manufacturer Part Number: MAX1508
• Description: Linear Li Battery Charger with Integrated Pass FET / Thermal Regulation / and ACOKin 3mm x 3mm TDFN
• Manufacturer: Maxim

The maximum charging current is programmed by an
external R
Select the R
where I
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:
Figure 2. Charge State Diagram
Thermal Regulation, and ACOK in 3mm x 3mm TDFN
Linear Li+ Battery Charger with Integrated Pass FET,
FAST
I
CHARGE
OF ISET
ISET
ISET
is in amps and R
V
> 20%
ISET
Applications Information
resistor connected from ISET to GND.
I
value based on the following formula:
FAST
_______________________________________________________________________________________
= (I
= 1461V / R
CHG
Charge-Current Selection
V
BATT
x R
< 2.4V
100% CHARGER CURRENT
10% CHARGE CURRENT
ISET
ISET
(MAX1508 ONLY)
PRECHARGE
FAST CHARGE
V
BATT
LED = ON
ISET
LED = ON
FULL BATT
is in ohms. ISET can
) / 1044
LED = OFF
< 2.5V
V
Ω
BATT
> 2.5V
FULL BATT CONTINUES
TO REGULATE BATT
I
CHARGE
UP TO 4.2V
OF ISET
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.
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.
< 10%
CHARGER = OFF
SHUTDOWN
LED = OFF
V
V
EN = HIGH
IN
BATT
> 7V +
> V
Thermal Regulation
ASYNCHRONOUS FROM
IN
+
V
BATT
ANYWHERE
EN = HIGH
V
IN
> 7V +
> VIN +
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