STBC21 datasheet(23/54 Pages) STMICROELECTRONICS

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STBC21

Detailed description

Doc ID 023256 Rev 1

23/54

Battery alarm occurs when:

●

TIMER-1 during pre-charge phase elapses;

●

TIMER-4 during 0V-charge phase elapses;

●

Overvoltage on the BAT pin occurs (VBAT > 4.23 V ± 20 mV, infringement of JEITA/PSE

regulation);

●

Undervoltage, during fast-charge or end of charge, on the BAT pin occurs (VBAT < 3.0

V);

●

Undervoltage on the TEMP pin occurs (VTEMP < 0.505 V, battery overheating);

●

Battery connection detection error occurs.

In all these cases the charge stops, the LEDs show a “Battery alarm” and a battery removal

is required to reset the charger. The battery removal is spotted because the voltage on the

TEMP pin rises above 2.425 V.

The battery alarm's flowchart is presented in

Figure 13.

Charger alarm occurs when:

●

Overvoltage on the VCC pin occurs (VCC > 9.0 V);

●

Undervoltage on the VCC pin occurs (VCC < 2.8 V, except for the power-up transition

when the charger is switched on);

●

Current increases over 1.1 A.

In these cases the charge is stopped, LEDs show a “charger alarm” and it's kept in this state

even if the battery is removed. A VCC removal is required to reset the charger.

The charger alarm's flowchart is depicted in

Figure 14.

Other alarms occur when:

●

VCC and VBATT are very close (VCC_ASD is lower than threshold);

●

Die temperature increases over 115 °C (thermal shutdown).

In these cases the battery charge is stopped, the LEDs continue to show “charge ongoing” if

the charger was in charge, and “end of charge” if the charger was in the termination phase

and the timers keep on counting. Once the alarm condition is removed, the charger restarts

the operations restoring the status it was in before the interruption.

During this phase, all other alarms (battery alarms and charger alarms) are active.

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