bq24200, bq24201, bq24202

bq24203, bq24204, bq24205

SLUS501A – OCTOBER 2001

11

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APPLICATION INFORMATION

battery charge current

Following a successful pre-conditioning, the bq2420x relies on an external current-limited supply to limit the

charge current to the cell. The bq2420x continues this phase until the battery reaches the voltage regulation

phase.

During this phase (and all other phases of operation) in order to protect the integrated powerFET, the internal

short circuit and thermal protection circuits are active.

battery voltage regulation

The voltage regulation feedback is through the BAT pin. This input is tied directly to the positive side of the

battery pack. The bq2420x monitors the battery-pack voltage between the BAT and VSS pins. The bq2420x

is offered in two fixed-voltage versions: 4.1 V and 4.2 V.

As a safety backup, the bq2420x also monitors the charge time in the voltage regulation mode. If taper current

STAT pin. Fault condition is cleared by POR or battery replacement. Note that the safety timer is reset if the

bq2420x is forced out of the voltage regulation mode.

charge termination and recharge

The bq2420x monitors the charging current during the voltage regulation phase. Once the taper threshold,

The bq2420x resets the taper timer in the event that the charge current returns above the taper threshold,

In addition to the taper current detection, the bq2420x terminates charge in the event that the charge current

After a charge termination, the bq2420x restarts the charge once the voltage on the BAT pin falls below the

sleep mode

The bq2420x enters the low-power sleep mode if the Vcc is removed from the circuit (i.e. the Vcc and IN pins

are floating). For applications where these pins are not floating, placing a low-power 10

Ω (1/16 W) between