Analog Integrated Circuit Device Data



Freescale Semiconductor

16

BC3770

5.3.7

Battery Recharge

Regardless of the AUTOSTOP bit status, the re-charge of the battery is able to be performed in two ways.

1. Automatic Enable

typical of 27 ms, the charger automatically resumes the charging. In this mode, the interrupt signal of “recharge” is reported to a processor

via the INTB pin. However if the battery voltage recovers above the threshold within 27 ms, the charging restart is not resumed and an

interrupt event is not reported. The threshold is a fixed value of -100 mV.

Figure 4. Re-charge Enabled in the Automatic Way

2. Manual Enable

The Application Processor (AP) is able to turn off the charger after the top-off or Done state is detected. Once the charger is enabled by

the processor and if the recharge conditions are met, the charger automatically charges the battery.

5.3.8

Soft-start

The BC3770 provides a soft-start in the transition from Pre-charge to Fast-charge mode to allow for a smaller voltage drop on VSYS and

to prevent input current and voltage transients. However, there is no soft-start in recharge mode. In summary, the following is the typical

charging profile where the following conditions are met in advance.

• A valid input is detected

• No AICL threshold detected

• All timers reset

• Input current limit > fast-charge current

• No SYS current

• Input current limit not detected

• No status changes on CHGEN = 1, CHGENB = LOW, SUSPEND = 0 and AUTOSTOP = 1

• Related interrupt bits not masked

• Deep battery with 2.0 V attached in advance

• Deglitch time excluded

Top-Off

detected

Re-

Charge

enabled

DONE

detected

27ms

deglitch

time