AN2370 Datasheet, PDF (10/14 Pages) STMicroelectronics – 800 mA standalone linear Li-Ion

Automatic recharge
6
Automatic recharge
AN2370
Once the charge cycle is terminated, the STC4054 continuously monitors the voltage on the
BAT pin using a comparator with a 2 ms filter time (t_RECHARGE). A charge cycle restarts
when the battery voltage falls below 4.05 V (which corresponds to approximately 80% to
90% battery capacity).
This ensures that the battery is kept at or near a fully charged condition and eliminates the
need for periodic charge cycle initiations. CHRG output enters a strong pulldown state
during recharge cycles.
Figure 9. State diagram of a typical charge cycle
POWER ON
Bat <2.9V
PROG
RECONNECTED
OR
UVLO
CONDITION
STOPS
TRICKLE CHARGE
MODE
1/10TH FULL
CURRENT
CHRG: STRONG
PULL-DOWN
SHUTDOWN MODE
CHRG: Hi-Z IN UVLO
WEAK PULL-DOWN
OTHERWISE
ICC DROPS TO <25µA
Bat >2.9V
CHARGE MODE
FULL CURRENT
CHRG: STRONG
PULL-DOWN
Bat >2.9V
PROG FLOATED
OR
UVLO
CONDITION
Prog<100mV
STANDBY MODE
NO CHARGE
CURRENT
CHRG: WEAK
PULL-DOWN
2.9V<Vbat<4.05V
10/14