RT9524 RICHTEK [Richtek Technology Corporation], RT9524 Datasheet - Page 9

• Manufacturer Part Number: RT9524
• Description: Linear Single Cell Li-Ion Battery Charger IC for Portable Applications
• Manufacturer: RICHTEK [Richtek Technology Corporation]

Battery Pre-Charge Current
During a charge cycle, if the battery voltage is below the
pre-charge threshold, the RT9524 enters the pre-charge
mode. This feature revives deeply discharged cells and
protects battery. Under USB100 Mode, the pre-charge
current is internally set to 95mA. When the RT9524 is
under USB500 and ISET Mode, the pre-charge current is
20% of fast-charge current set by external resistor R
Battery Fast-Charge Current
ISET Mode
The RT9524 offers ISET pin to program the charge current.
The resistor R
parameter K
DS9524-01 April 2011
I
Charge
1400
1200
1000
800
600
400
200
0
=
Programmed
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3
Pre-charge
Current
Current
Battery
Charge
Charge
Mode
K
R
ISEF
ISET
ISET
ISET
is specified in the specification table.
; K
is connected to ISET and GND. The
Constant
Precharge
Threshold
ISEF
Current
Mode
Figure 2
Figure 3
= 530
R
R
SET
SET
Constant
Regulation
Voltage
threshold
Mode
Voltage
Battery
pull High
(k ∠ )
(kΩ)
CHG_S
Battery
4.2V
Full
Recharge
Phase
Time
ISET
.
USB500 and USB100 Mode
The fast-charge current is 95mA in USB100 mode and
395mA in USB500 mode. Note that if the fast-charge
current set by external resistor is smaller than that in
USB500 mode (395mA), the RT9524 charges the battery
in ISET mode.
Battery Voltage Regulation (CV Mode)
The battery voltage regulation feedback is through the
BATT pin. The RT9524 monitors the battery voltage
between BATT and GND pins. When the battery voltage
closes in on the battery regulation voltage threshold, the
voltage regulation phase begins and the charging current
begins to taper down. When the charging current falls
below the programmed end-of-charge current threshold,
the CHGSB pin goes high to indicate the termination of
charge cycle.
The end-of-charge current threshold is set by the IEOC
pin. The resistor R
The parameters K
specification table.
The current threshold of IEOC (%) is defined as the
percentage of fast-charge current set by R
CHGSB pin is pulled high, the RT9524 still monitors the
battery voltage. Charge current is resumed when the
battery voltage goes to lower than the battery regulation
voltage threshold.
Factory Mode
The RT9524 provides factory mode for supplies up to 2.3A
for powering external loads with no battery installed and
BATT is regulated to 4.2V. The factory mode allows the
user to supply system power with no battery connected.
In factory mode, thermal regulation is disabled but thermal
protection (155°C) is still active. When using currents
greater than 1.5A in factory mode, the user must limit the
duty cycle at the maximum current to 20% with a
maximum period of 10ms.
LDO
The RT9524 integrates one low dropout linear regulator
(LDO) that supplies up to 50mA. The LDO is active
whenever the input voltage is between POR threshold and
I
EOC
(%) =
R
K
EOC
EOC
; K
EOC
EOC
EOC
is connected to IEOC and GND.
and IEOC are specified in the
= 200
RT9524
www.richtek.com
ISET
. After the
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