LP4068-01

Jan.-2019

www.lowpowersemi.com

Page 6 of 8

Preliminary Datasheet

LP4068

Application Information

Input Voltage Range

The LP4068 has built-in input voltage surge protection as high

as +28V. The charger IC will be automatically disabled when

the input voltage is higher than 7V.A charge cycle begins

when the voltage at the VIN pin rises above the 4.4V level,

when a battery is connected to the charger output. If the BAT

pin is less than 2.6V, the charger enters trickle charge mode.

In this mode, the LP4068 supplies approximately 1/10 the

ISET programmed charge current to bring the battery voltage

up to a safe level for full current charging. When the BAT pin

voltage rises above 2.6V, the charger enters constant-current

mode(CC), where the ISET programmed charge current is

supplied to the battery. When the BAT pin approaches the

final float voltage, the LP4068 enters constant-voltage

mode(CV) and the charge current begins to decrease, and the

battery full indication is set when the charge current in the CV

mode is reduced to the programmed full battery current

(1/10).

Charge Termination

A charge cycle is terminated when the charge current falls to

1/10th the ISET programmed value after the final float voltage

is reached. This condition is detected by using an internal,

filtered comparator to monitor the ISET pin. When the ISET

1ms), charging is terminated.

ISET programming Charge Current

connecting from the ISET pin to GND. The relationship of the

charge current and the programming resistance is established

Automatic Recharge

Once the charge cycle is terminated, the LP4068 continuously

monitors the voltage on the BAT pin. A charge cycle restarts

when the battery voltage falls below 4.05V (which

corresponds to approximately 80% to 90% battery capacity).

This ensures that the battery is kept at or near a fully charged

condition and eliminates the need for periodic charge cycle

initiations.

Charge Status Indicator(CHRG/FULL)

After application of a 5V source, the input voltage rises above

pull-down (~5mA) and high impedance. The strong pull-down

state indicates that the LP4068 is in a charge cycle. When the

charger is entered CV mode and once the charge current has

CHRG pin will become high impedance.

Function

CHRG

FULL

Charging

Low

High

Charge Finish

High

Low

Thermal Limiting

programmed charge current if the die temperature attempts to

rise above a preset value of approximately 125°C. This

feature protects the LP4068 from excessive temperature and

allows the user to push the limits of the power handling

capability of a given circuit board without risk of damaging the

LP4068. The charge current can be set according to typical

(not worst-case) ambient temperature with the assurance that

the charger will automatically reduce the current in worst-case

conditions.