BC3770 Datasheet, PDF (16/45 Pages) Freescale Semiconductor, Inc – 2.0 A Switch-Mode Charger

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
After a top-off threshold or Done is detected and the battery voltage drops below the recharge threshold, V_RCH, over the deglitch time, a
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.
Top-Off
detected
DONE
detected
VRCH detected
27ms
deglitch
time
Re-
Charge
enabled
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
• V_RCH = -100 mV
• Related interrupt bits not masked
• Deep battery with 2.0 V attached in advance
• Deglitch time excluded
Analog Integrated Circuit Device Data
Freescale Semiconductor
BC3770
16