LP28009 Datasheet, PDF (10/12 Pages) Lowpower Semiconductor inc – Internal Integrate P-MOSFETs

Preliminary Datasheet
Application Information
Automatically Power Source Selection
The LP28009 is a battery charger IC which is designed
for Li-ion Battery with 4.2V rated voltage.
ACIN Mode : When the ACIN input voltage is higher
than the UVP voltage level (4.4V), the LP28009 will
turn on ACINP-MOSFET. Sleep Mode : The LP28009
will enter Sleep Mode when ACIN input voltage are
removed. This feature provides low leakage current
from the battery during the absence of input supply.
LP28009
ACIN Over Voltage Protection
The ACIN input voltage is monitored by an internal
OVP comparator. The comparator has an accurate
reference of 2.5V from the band-gap reference. The
OVP threshold is set by the internal resistive. The
protection threshold is set to 6.5V. When the input
voltage exceeds the threshold, the comparator outputs
a logic signal to turn off the power P-MOSFET to
prevent the high input voltage from damaging the
electronics in the handheld system. When the input
over voltage condition is removed (ACIN < 6V), the
comparator re-enables the output by running through
the soft-start.
Fast-Charge Current Setting
The LP28009 offers ISETA pin to determine the ACIN
charge rate from 100mA to 1.2A. The charge current
can be calculated as following equation.
Pre- Charge Current Setting
During a charge cycle if the battery voltage is below
the VPRECH threshold, the LP28009 applies a
pre-charge mode to the battery. This feature revives
deeply discharged cell sand protects battery life. The
LP28009 internal determines the pre-charge rate as
10% of the fast-charge current.
Battery Voltage Regulation
The LP28009 monitors the battery voltage through the
BATT pin. Once the battery voltage level closes to the
VREG threshold, the LP28009 voltage enters constant
phase and the charging current begins to taper down.
When battery voltage is over the VREG threshold, the
LP28009 will stop charge and keep to monitor the
battery voltage. However, when the battery voltage
decreases 100mV below the VREG, it will be
recharged to keep the battery voltage. Charge Status
Outputs. The open-drain CHG_S and PGOOD 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.
LP28009 – 02
May.-2013
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