LP28009 datasheet(10/12 Pages) POWER

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Preliminary Datasheet

LP28009

LP28009 – 02

May.-2013

Email: marketing@lowpowersemi.com

www.lowpowersemi.com

Page 10 of 12

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.

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.

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