LP28400ACQVF datasheet(7/10 Pages) POWER

7 / 10 page

LP28400A – 02

Sep.-2016

Email: marketing@lowpowersemi.com

www.lowpowersemi.com

Page 7 of 10

Preliminary Datasheet

LP28400A

Function Description

LP28400A is a wide range VIN(3V-12V), 1.5A

two-cell asynchronous boost Li-Ion battery charger

integrates 1MHz switching frequency and full

protection functions. The charge current up to 1.5A

can be programmed by using the external resistor for

different portable applications and indicates the

charger current information simultaneous.

It also has an adaptive input current limit for safety

battery charge operation. It consists of 18V rating

FETs with extremely low ON resistance to achieve

high charge efficiency and simple peripheral circuit

design.

Battery Charge Mode

If the plug in input voltage VIN is higher than VBAT,

the switching block will stop work to keep LX pin in

high resistance and PB will control the external

PMOS` VGS to match the battery voltage. Under this

condition, the Boost charger function stops work and

regulates the external FET works in linear charge

mode. Whether the circuit work in Boost mode or

Linear mode, the constant charge current is

programmed by Rsense with:

SENSE

RSENSE



BAT

Which VRSENSE=50mV

The circuit would work in trickle charge mode when

battery voltage below 6V with VRSENSE=10mV. The

terminal charge current would be programmed by

VRSENSE=5mV.

During the charging mode, constant (trickle) charging

current loop is active first. When VBAT equals to

constant voltage threshold, constant voltage loop

takes over and pull down the charging current. When

IBAT is lower than the termination current threshold

ITERM, the main FET of boost charger is turned off

firstly. External PMOS are turned off when the

current is down to zero. Then, LP28400A is waiting

for recharge mode.

Input Source Qualification

After REGN amplifier powers up, the LP28400A

checks the current capability of the input source. The

input source has to meet the VREG>1V to enable the

chip.

Number of Charge Cell Selection (QFN-16)

The number of charge cell can be programmed by

changing the connection of CELLS Pin (QFN-16

package only). Connect CELLS Pin to GND is

provide for 3 cells charging, leave floating for 2 cells,

and connect to VL for 4 cells.

CELLS Pin Connected

Charge Cells

Floating(No connected)

GND

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