RT9524 RICHTEK [Richtek Technology Corporation], RT9524 Datasheet - Page 10

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

RT9524
OVP threshold. It is not affected by the EN/SET input.
Note that the LDO current is independence and not
monitored by the charge current limit.
Charge Status Outputs (CHGSB and PGB)
The open-drain CHGSB and PGB outputs indicate various
charger operations as shown in the following table. These
status pins can be used to drive LEDs or communicate to
the host processor. Note that ON indicates the open-drain
transistor is turned on and LED is bright.
Sleep Mode
The RT9524 enters sleep mode if the power is removed
from the input. This feature prevents draining the battery
during the absence of input supply.
Temperature Regulation and Thermal Protection
In order to maximize charge rate, the RT9524 features a
junction temperature regulation loop. If the power
dissipation of the IC results in a junction temperature
greater than the thermal regulation threshold (125°C), the
RT9524 limits the charge current in order to maintain a
junction temperature around the thermal regulation
threshold (125°C). The RT9524 monitors the junction
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10
Input OVP
Input UVLO
Charge (CC Mode and CV Mode)
Charge Done (IFULL)
Entering OVP
(V
Leaving OVP
(V
Entering SLEEP
(V
Leaving SLEEP
(V
Entering UVLO
(V
Leaving UVLO
(V
IN
IN
IN
IN
IN
IN
= 5.5V→10V)
= 10V→5.5V)
= 5.5V→3.6V)
= 3.6V→5.5V)
= 5.5V→2.5V)
= 2.5V→5.5V)
Condition
Condition
Table 2
EN/SET is
PGB Deglitches Time
500μs
500μs
230μs
High
0
0
0
CHGSB
OFF
OFF
OFF
ON
EN/SET is
100μs
450μs
500μs
230μs
32ms
Low
0
PGB
OFF
OFF
ON
ON
temperature, T
from the input if T
continues until junction temperature falls below thermal
regulation threshold (125°C) by the hysteresis level. This
feature prevents maximum power dissipation from
exceeding typical design conditions.
Selecting the Input and Output Capacitors
In most applications, all that is needed is a high-frequency
decoupling capacitor on the input. A 1μF ceramic capacitor,
placed in close proximity to input to GND, works well. In
some applications depending on the power supply
characteristics and cable length, it may be necessary to
add an additional 10μF ceramic capacitor to the input.
The RT9524 requires a small output capacitor for loop
stability. A typical 1μF ceramic capacitor placed between
the BATT pin and GND is sufficient.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature. The maximum
power dissipation depends on thermal resistance of the
IC package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature. The
maximum power dissipation can be calculated by the
following formula :
P
where T
temperature, T
junction to ambient thermal resistance.
For recommended operating conditions specification of
RT9524, the maximum junction temperature is 125°C and
T
ambient thermal resistance, θ
WDFN-10L 3x2 packages, the thermal resistance, θ
90°C/W on a standard JEDEC 51-7 four-layer thermal test
board. The maximum power dissipation at T
be calculated by the following formula :
P
WDFN-10L 3x2 package
The maximum power dissipation depends on operating
ambient temperature for fixed T
resistance, θ
A
D(MAX)
D(MAX)
is the maximum ambient temperature. The junction to
= (T
= (125°C − 25°C) / (90°C/W) = 1.111W for
J(MAX)
J(MAX)
JA
A
. For RT9524 package, the derating curve
J
, of the die and disconnects the battery
is the ambient temperature, and θ
is the maximum operation junction
− T
J
A
) / θ
exceeds 125°C. This operation
JA
JA
, is layout dependent. For
DS9524-01 April 2011
J(MAX)
and thermal
A
= 25°C can
JA
is the
JA
, is