RT9516 RICHTEK [Richtek Technology Corporation], RT9516 Datasheet - Page 9

• Manufacturer Part Number: RT9516
• Description: Linear Single Cell Li-lon Battery Charger with Single Input Supply for Portable Applications
• Manufacturer: RICHTEK [Richtek Technology Corporation]

c. Battery Voltage Regulation (CV Mode)
The battery voltage regulation feedback is through the
BATT pin. The RT9516 monitors the battery voltage
between the BATT and GND pins. When battery voltage is
close to battery regulation voltage threshold, the voltage
regulation phase begins and the charging current begins
to taper down. When battery voltage is over battery
regulation voltage threshold and charge mode stops, the
RT9516 still monitors the battery voltage. Charge current
is resumed when the battery voltage under battery
regulation voltage threshold.
Sleep Mode
The RT9516 enters the sleep mode if both AC and USB
are removed from the input. This feature prevents draining
the battery during the absence of input supply.
Power Good
The open-drain output pin is used to indicate the input
voltage status. The PGOOD output asserts low when
V
can be used to drive LED or communicate to the host
processor. Note that ON indicates the open-drain transistor
is turned on and LED is bright.
Auto-Booting
The RT9516 has an internal “OR” gate that generates an
enable signal for system booting. The battery supplies
power to the “OR” gate, the RT9516 will keep BATT pin
voltage to supply the “OR” gate function when the battery
isn connected at BATT pin. The first input is the AC_PG
and the second input is an external signal (ABI). When
the (V
ABI signal is driven by an external system, when external
signal is floating, the ABI has an internal pull low resistor.
DS9516-01 April 2011
IN
> 4.25V and (V
IN
− V
BATT
AC_PG
) > 90mV, the AC_PG signal is high. The
200k
IN
− V
BATT
ABI
Figure 3
) > 40mV. These PGOOD pin
V
BATT
ABO
Temperature Regulation and Thermal Protection
In order to maximize charge rate, the RT9516 features a
junction temperature regulation loop. If the power
dissipation of the IC results in a junction temperature that
is greater than the thermal regulation threshold (115°C),
the RT9516 throttles back on the charge current in order
to maintain a junction temperature around the thermal
regulation threshold (115°C). The RT9516 monitors the
junction temperature, T
battery from the input if T
continues until junction temperature falls below thermal
regulation threshold (115°C by the hysteresis level. This
feature prevents the maximum power dissipation from
exceeding typical design conditions.
Selecting the Input and Output Capacitors
In most applications, a high-frequency decoupling capacitor
on the input.(1μF ceramic capacitor), placed in close
proximity to the input 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 RT9516 requires a
small output capacitor for loop stability. A 1μF ceramic
capacitor placed between the BATT pin and GND is typically
sufficient.
Thermal Conderations
The maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
junction to ambient. The maximum power dissipation can
be calculated by following formula :
P
Where T
temperature, T
the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT9516, where T
ambient temperature. The junction to ambient thermal
resistance
the standard JEDEC 51-3 single-layer thermal test board.
D(MAX)
= (T
J(MAX)
θ
J(MAX)
JA
for WDFN-8L 2x2 package is 165°C/W on
A
is the ambient temperature and the
is the maximum operation junction
− T
J(MAX)
A
)
/θ
J
is 125° C and T
, of the die and disconnects the
J
JA
exceeds 115°C. This operation
A
RT9516
www.richtek.com
is the operated
θ
JA
is
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