LP28014

LP28014 – 00

Oct.-2018

www.lowpowersemi.com

Page 5 of 7

Application Information

Input Voltage Range

The LP28014 has built-in input voltage surge protection as

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

when the input voltage is lower than 3.3V or higher than 7.0V.

The open-drain PG Pin is used to indicate an input power

good condition (3.3V<VIN<7.0V). If the input voltage is lower

than the battery voltage, the IC is also disabled to prevent the

battery from draining.

A charge cycle begins when the voltage at the VIN pin rises

above the UVLO threshold 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

LP28014 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 LP28014 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 (IBF).

ISET programming Charge Current

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

charge current and the programming resistance is established

by the following table.

Termination charge current programmed

The battery charge Termination current threshold (IBF) is

programmed by connecting a resistor RBF from the IBF pin to

GND:

Automatic Recharge

Once the charge cycle is terminated, the LP28014

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.

Enable Function

The LP28014 features an enable/disable function. An input

“Low” signal at EN pin or if this pin is floating will enable the IC.

To assure the charger will switch on, the EN turn on control

level must below 0.4 volts. The charger IC r will go into the

shutdown mode when the voltage on the EN pin is greater

than 1.4 volts. If the enable function is not needed in a specific

application, it may be tied to GND or floating to keep the

charge IC in a continuously on state.

Thermal Limiting

An internal thermal feedback loop reduces the I SET rammed

charge current if the die temperature attempts to rise above a

preset value of approximately 125°C. This feature protects the

LP28014 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 LP28014. 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.