MP2603 – SINGLE CELL 150mA LINEAR LI-ION BATTERY CHARGER
MP2603 Rev. 1.01 www.MonolithicPower.com 7
1/31/2013 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
OPERATION
The MP2603 is enabled with a minimum input
supply voltage of 3.5V. This power supply must
also be higher than both the UVLO threshold
and the battery voltage. There is an internal
500kΩ pull-down resistor connecting the IN and
GND pins. The MP2603 provides CC/CV
charge algorithms to automatically change
modes depending on the battery status. Figure
2 shows the typical charging procedure for the
MP2603.
Trickle
Charging
Charge
Start
Charge
End
Soft-Start
Time
Thermal
Regulation
CC
Mode
CV
Mode
10% of I
CHG
90% of I
CHG
I
CHG
2.6V
4.2V
V
BATT
V
BATT
I
BATT
I
BATT
Figure 2—MP2603 Typical Charging
Procedure
The charge current, I
CHG
, is programmed by
connecting a resistor (R
PGM
) from the I
PGM
pin to
ground. The relationship of the charge current
and the programming resistance is established
by the following equation and graph. The
Table1 lists the typical application setting of
Ichg.
PGM
CHG
R
k53.2
mA150I
Ω
×=
(1)
Table 1— R
PGM
and I
CHG
Relationship
R
PGM
(kΩ) I
CHG
(mA)
12.4 30
7.2 52
4.99 76
3.74 101
2.5 151
180
150
120
90
60
30
0
0.0 0.1 0.2 0.3 0.4 0.5
Charge Current vs
1/R
PGM
Resistance
CHARGE CURRENT (mA)
Figure 3— Charge Current vs 1/R
PGM
Resistance
When battery voltage falls below the trickle
threshold (2.6V), charge current is limited to
10% of the programmed value to trickle charge
the fully depleted battery. After the battery
voltage reaches 2.6V, the charger begins to
charge at the constant current of the
programmed value (I
CHG
). This is referred to as
Constant Current (CC) mode. Once the battery
voltage reaches 4.2V, the charger will operate
in the Constant Voltage (CV) mode until the
battery is fully charged.
Charge Status (CHGZ)
The open-drain CHGZ pin monitors charge
status by connecting to V
BATT
through an LED
and/or a resistor. The end-of-charge, or battery
full, is indicated by the CHGZ pin changing from
LOW to HIGH (i.e. LED turns off) when I
CHG
decreases to 10% of the programmed value.
Thermal Protection
To prevent overheating, the MP2603
automatically limits the die temperature to
130°C by reducing the internal current-setting
reference voltage. In the thermal protection
mode, the charge current reduces automatically,
but remains continuous.
