Technical data

Hardware and Firmware

Firmware Description

DRM043/D — Rev 0 Designer Reference Manual

MOTOROLA Hardware and Firmware 13

2.3 Firmware Description

2.3.1 Battery inserted detection.

Normally, a Lithium-ion battery has 3 terminals, B+, B- and T. The

terminal T can be one of the terminals for temperature sensor or a

dummy resistor. The battery charger can sense the voltage at the

corresponding T of J1 (refer to charger schematic at 3.5). When the

battery is removed, the voltage that appears at T will be pulled up to Vdd

by the 10K resistor, i.e., it is in high state. When the battery is inserted,

the voltage at T will be equal to Z1/(Z1+10K) x Vdd. Charger can then

sense insertion of the battery insertion by checking the voltage at T by

ADC.

When battery insertion is detected, the firmware will go on to check the

inserted battery's voltage and temperature. If it falls in the valid range,

then proceed to charging mode.

Vbat < 1.0V No charging, bad battery, flashing LEDs

Vbat > 4.0V Battery full, no charging, green LED on

1.0V < Vbat < 2.5V Trickle charge, red LED on

2.5V <Vbat < 4.0V Fast charge, red LED on

Vtemp < 0 C No charging. Flashing LEDs

Vtemp > 45 C No charging. Flashing LEDs

I_charge > 500mA Over current, stop charging, flashing LEDs

2.3.2 Trickle charge

If the battery voltage is <2.5V, then go to trickle charge. The current for

trickle charge is set to 0.1C to 0.2C which equals to the 10% or 20% of

the battery's rate capacity, and the max. Charge time is 10 mins. If within

10 mins time, the battery voltage raise above 2.5V, then it means the

battery is a good battery and the charger can then switch to fast charging

Frees

cale Semiconductor,

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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