AP4305 datasheet(11/32 Pages) AKM

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[AP4305]

Rev 0.5.0

3. Charge Functions

3.1. Charge Control

Charge Control operation flows are shown below.

3.1.1. Battery Connection Check

The AP4305 monitors battery connection by using the TEMP input voltage value. If the TEMP input voltage is

within a given range, the AP4305 determines that “a battery is connected” and if the TEMP input voltage is

outside the given range, the AP4305 determines that “no battery is connected”. Charging will not be started

while a battery is determined as not connected.

The voltages for determining connection are VBTOP and VBBOT in Electrical Characteristics.

3.1.2. Battery Temperature Check

Battery temperature is checked. If the battery temperature is not within the charge inhibition range (More than

TLOW and Lower than THIGH), the AP4305 transitions to Trickle Charge 1 to start trickle charge. If the battery

temperature is determined to be within the charge inhibition range (Less than TLOW and More than THIGH), the

battery temperature is checked again after a certain period of time.

3.1.3. Trickle Charge 1

Assuming an over discharged state of the battery, constant-current charging is started at a current that does

not damage the battery. At the same time, the internal timer starts counting. The battery voltage is periodically

monitored, and when VTRKL is exceeded, the AP4305 transitions to Trickle-charge 2. If the battery voltage

does not exceed VTRKL even when the Trickle Charge 1 time-out time passes, the AP4305 determines that the

battery is abnormal and transitions to “Battery Abnormality”.

3.1.4. Trickle Charge 2

Until the battery voltage reaches the voltage that allows fast charge (VCC), constant-current charging is

continued at a current that does not damage the battery. The internal timer is reset and starts counting again.

The AP4305 periodically monitors the battery voltage, and when VCC is exceeded, transitions to “Trickle

Charge Check”. If the battery voltage does not exceed VCC even when the Trickle-charge 2 time-out time

passes, the AP4305 determines that the battery is abnormal and transitions to “Battery Abnormality”.

3.1.5. Trickle Charge Check

After the termination of trickle charge, whether battery voltage is checked. Depending on this, the operation

after the full charge voltage check is chosen.

3.1.6. Fast Charge

There are two states: constant-current charging and constant-voltage charging. Immediately after state

transition, the fast charge timer starts counting and constant-current charging starts. When the battery voltage

increases and reaches VCV, the AP4305 transitions to constant-voltage charging. Normally in constant-voltage

charging, the charging current decreases as the charge becomes close to full charge. When the charging

current drops to or below IEOC, the AP4305 determines that the battery is fully charged and stops fast-charge if

the operation mode is in constant-voltage charging. (Option that full charge current is not detected while

detecting input current limit is selectable by I2C interface.)

The state transitions to “Full Charge Voltage Check”. Even if the charge does not reach full charge after the

fast charge time-out time passes, the AP4305 stops charging and transitions to “Full Charge Voltage Check”.

If the battery voltage drops to or below VTRKL during charging, the AP4305 determines that the battery may

have been disconnected and transitions to the Battery Abnormality state.

AP4305 Datasheet(PDF) 11 Page - Asahi Kasei Microsystems

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