LP28006 datasheet(8/11 Pages) POWER

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Preliminary Datasheet

LP28006

LP28006 – 00 Ver. 1.0 Datasheet

Feb.-2010

www.lowpowersemi.com

Page 8 of 11

Application Information

Automatically Power Source Selection

The LP28006 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

LP28006 will turn on ACINP-MOSFET. Sleep

Mode : The LP28006 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.

Battery Temperature Monitoring

The LP28006 continuously monitors battery

temperature by measuring the voltage between the

TS and GND pins. The LP28006 has an internal

current source to provide the bias for the most

common 10kΩ negative-temperature coefficient

thermal resistor (NTC) (see Figure 1). The LP28006

compares the voltage on the TS pin against the

internal VTS_HIGH and VTS_LOW thresholds to

determine if charging is allowed.

When the temperature outside the VTS_HIGH and

VTS_LOW thresholds is detected, the device will

immediately stop the charge. The LP28006 stops

charge and keep monitoring the battery temperature

when the temperature sense input voltage is back to

the threshold between VTS_HIGH and VTS_LOW,

the charger will be resumed. Charge is resumed

when the temperature returns to the normal range.

However the user may modify thresholds by the

negative-temperature coefficient thermal resistor or

adding two external resistors. (see Figure 2.)The

capacitor should be placed close to TS(Pin 9) and

connected to the ground plane. The capacitance

value(0.1uF to 10uF) should be selected according

to the quality of PCB layout. It is recommended to

use 10uF if the layout is poor if prevent noise.

Fast-Charge Current Setting The LP28006 offers

ISETA pin to determine the ACIN charge rate from

100mA to 1.2A. The charge current can be

calculated as following equation.

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