LP3913 datasheet(39/70 Pages) TI1

39 / 70 page

hiRef

loRef

ntc

Logic

charger

control

Battery discharge

Constant Voltage Charging

Battery charge current

Battery voltage

Time

Full Rate

Topoff

RED LED

GREEN LED

OFF

End-Of-Charge

(EOC)

50% Duty cycle

Pre-qualification

2.85V

Charging restart voltage

3.9V, 4.0V or 4.2V

Termination voltage

4.1V, 4.2V or 4.38V

1.0C

0.1 C PREQUAL CURRENT

0.05 C EOC CURRENT

LP3913

www.ti.com

SNVS489I – NOVEMBER 2006 – REVISED SEPTEMBER 2013

Battery Temperature Monitoring (TS pin)

The LP3913 is equipped with a battery thermistor terminal to continuously monitor the battery temperature by

measuring the voltage between the TS pin and GND. With the TS pin connected to the battery thermistor,

charging is allowed only if the battery temperature is within the acceptable temperature range set by a pair of

internal comparators inside the LP3910. The temperature window is 0°C–45°C or 0°C–50°C, depending on the

setting of D2 of the Charger Supervisory (CHSPV) register. There is 3ºC of temperature hysteresis associated

with each temperature threshold. The default temperature range is 0°C–50°C and can be changed to 0°C–45°C

by setting bit D3 in the CHSPV register. If the battery temperature is out of range, STAT2, STAT1 and STAT0

bits in the CHSPV Register are set to logic1, logic0, logic0, and charging is suspended.

The TS pin is only active during charging and draws no current from the battery when no external power source

is present.

If the TS pin is not used in the application, it should be connected to GND through a 100 kΩ pulldown resistor.

When the TS pin is left floating (battery removal), then the charger will be disabled as the TS voltage exceeds the

lower temperature limit.

Disabling Charger

Charging can be safely interrupted by clearing the Charge enable bit D1 in the Charge Control Register and can

subsequently resume upon setting this bit. When the charger is disabled, STAT2, STAT1, and STAT0 bits in the

CHSPV register are set to logic 0.

Safety Timer

In order to prevent endless charging, which could degrade the battery quality and life time, the LP3913 contains

a safety timer that limits charging regardless whether the battery has reached its full capacity or not. In

prequalification the safety timer is 1 hour. In full rate or constant voltage charging the safety timer is a maximum

of 10 hours minus the time in prequalification.

When the timer times out of uninterrupted charging, an IRQ is generated to alert system processor. The status of

the timer can also be polled by reading the IRQ register if the system doesn’t support hardware interrupts.

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