isl9203crz-t Intersil Corporation, isl9203crz-t Datasheet - Page 10

• Manufacturer Part Number: isl9203crz-t
• Description: Li-ion/li Polymer Battery Charger
• Manufacturer: Intersil Corporation

Theory of Operation
The ISL9203 is an integrated charger for single-cell Li-ion or
Li-polymer batteries. The ISL9203 functions as a traditional
linear charger when powered with a voltage-source adapter.
When powered with a current-limited adapter, the charger
minimizes the thermal dissipation commonly seen in
traditional linear chargers.
As a linear charger, the ISL9203 charges a battery in the
popular constant current (CC) and constant voltage (CV)
profile. The constant charge current I
up to 1.5A with an external resistor. The charge voltage V
has 1% accuracy over the entire recommended operating
condition range. The charger always preconditions the
battery with 10% of the programmed current at the beginning
of a charge cycle, until the battery voltage is verified to be
above the minimum fast charge voltage, V
current preconditioning charge mode is named trickle mode.
The verification takes 15 cycles of an internal oscillator
whose period is programmable with the timing capacitor. A
thermal-foldback feature removes the thermal concern
typically seen in linear chargers. The charger reduces the
charge current automatically as the IC internal temperature
rises above 100°C to prevent further temperature rise. The
thermal-foldback feature guarantees safe operation when
the printed circuit board (PCB) is space limited for thermal
dissipation.
The charger offers a safety timer for setting the fast charge
time (TIMEOUT) limit to prevent charging a dead battery for
an extensively long time. The trickle mode is limited to 1/8 of
TIMEOUT.
The charger automatically re-charges the battery when the
battery voltage drops below a recharge threshold. When the
wall adapter is not present, the ISL9203 draws less than 1
current from the battery.
FIGURE 18. TYPICAL CHARGE CURVES USING A
I
REF
V
V
I
V
REF
/10
MIN
P
P
P
CH
IN
1
2
3
Trickle
Mode
Input Voltage
CONSTANT-VOLTAGE ADAPTER
Constant Current
Mode
10
TIMEOUT
Constant Voltage
REF
Power Dissipation
Mode
Battery Voltage
Charge Current
is programmable
MIN
. This low-
Inhibit
CH
P
A
ISL9203
Three indication pins are available from the charger to
indicate the charge status. The V2P8 outputs a 2.8V dc
voltage when the input voltage is above the power-on reset
(POR) level and can be used as the power-present
indication. This pin is capable of sourcing a 2mA current, so
it can also be used to bias external circuits.
The STATUS pin is an open-drain logic output that turns
LOW at the beginning of a charge cycle until the end-of-
charge (EOC) condition is qualified. The EOC condition is:
the battery voltage rises above the recharge threshold and
the charge current falls below a user-programmable EOC
current threshold. Once the EOC condition is qualified, the
STATUS output rises to HIGH and is latched. The latch is
released at the beginning of a charge or re-charge cycle.
The open-drain FAULT pin turns low when a charge time
fault occurs or when the IREF pin is pulled below 0.35V or
above 1.4V.
Figure 18 shows the typical charge curves in a traditional
linear charger powered with a constant-voltage adapter.
From the top to bottom, the curves represent the constant
input voltage, the battery voltage, the charge current and the
power dissipation in the charger. The power dissipation P
is given by the following equation:
where I
dissipation occurs during the beginning of the CC mode. The
maximum power the IC is capable of dissipating is
dependent on the thermal impedance of the printed-circuit
board (PCB). Figure 18 shows, with dotted lines, two cases
that the charge currents are limited by the maximum power
dissipation capability due to the thermal foldback.
P
FIGURE 19. TYPICAL CHARGE CURVES USING A CURRENT-
CH
I
REF
V
V
I
=
I
V
REF
/10
MIN
LIM
P
P
CH
CHARGE
IN
1
2
V
IN
Trickle
Mode
–
LIMITED ADAPTER
V
BAT
is the charge current. The maximum power
Constant Current
Input Voltage
I
˜
CHARGE
Mode
TIMEOUT
Constant Voltage
Power Dissipation
Mode
Battery Voltage
Charge Current
February 3, 2005
Inhibit
FN6106.0
(EQ. 1)
CH