®
ACT5830
Rev 2, 20-Jan-11
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
FUNCTIONAL DESCRIPTIONS CONT’D
TOP-OFF State
Charge Safety Timer
In the TOP-OFF state, the cell is charged in
constant-voltage (CV) mode. With the charge
current limited by the internal chemistry of the cell,
decreases as charging continues. During a normal
charging cycle charging proceeds until the charge
current decreases beyond the End-Of-Charge
(EOC) threshold, defined as 10% of ISET. When
this happens, the state machine terminates the
charge cycle and jumps to the SLEEP state.
While monitoring the charge cycle, the ACT5830
utilizes a charge safety timer to help identify
damaged cells and to ensure that the cell is
charged safely. Three timeout options of 1 hour,
1.43 hours, and
2 hours are available, as
programmed by the CHGR/TIMOSET register, and
a timer-disable option is also available for systems
that do not require the ACT5830 to control charge
timeouts.
The bit assignments for each timeout period are set
as follows:
SLEEP State
In SLEEP mode the ACT5830 presents a high-
impedance to the battery, allowing the cell to “relax”
and minimizing battery leakage current. The
ACT5830 continues to monitor the cell voltage,
however, so that it can re-initiate charging cycles as
necessary to ensure that the cell remains fully
charged. Under normal operation, the state
machine initiates a new charging cycle by jumping
to the FAST-CHARGE state when VBAT drops below
the Charge Termination Threshold (programmed by
VSET) by more than the Charge Restart Threshold
of 200mV (typ).
Table 12:
TIMOSET[ ] Timeout Period Options
TIMOSET PRECONDITION TOTAL CHARGING
[1:0 ]
TIMEOUT
TIMEOUT
0
0
1
0
1
1 hour
3 hours
0
1
1
1.43 hours
2 hours
4.3 hours
6 hours
INFINITE
INFINITE
SUSPEND State
CHGR State-Machine
The ACT5830 features a user-selectable suspend-
charge mode (SUSCHG), which disables the
charger but keeps other circuitry functional.
Charging continues in the SUSPEND state until
CHGR/SUSPEND is cleared, at which point the
charge timer is reset and the state machine jumps
to the PRECHARGE state.
PRECONDITION State
A
new charging cycle begins with the
PRECONDITION state. In this state, the cell is
charged at a reduced current of 10% of ISET, the
programmed fast charge current. During a normal
charge cycle, charging continues at this rate until
VBAT reaches the Precondition Threshold Voltage of
2.9V (typ), at which point the charging state
machine jumps to its FAST-CHARGE state. If VBAT
does not reach the Precondition Threshold Voltage
before the Precondition timeout period expires, then
a damaged cell is detected and the state machine
jumps to the TIMEOUT-FAULT State.
Suspend charge by setting CHGR/SUSCHG = [1].
Permit charging by clearing CHGR/SUSCHG to [0].
TIMEOUT-FAULT State
In order to prevent continued operation with a
damaged cell, there is no direct path to resume
charging once a Timeout Fault occurs. In order to
resume charging, the state machine must jump to
the SUSPEND state as a result of any of the
following events:
FAST-CHARGE State
In FAST-CHARGE mode, the charger operates in
constant-current (CC) mode and charges the cell at
the current programmed by CHGR/ISET. During a
normal charge cycle fast-charge continues until
VBAT reaches the termination voltage programmed
by VSET, at which point the state machine jumps to
the TOPOFF state. If VBAT does not reach VSET
before the total time out period expires then the
state-machine will jump to the “SLEEP” state.
1) Microprocessor Sets CHGR/SUSCHG to [1],
2) Microprocessor Pulls nENCHG high,
The input supply is removed or the input supply
voltage drops below the UVLO threshold (4V), or
the battery is removed. Once any of these events
occur, the state machine jumps to the SUSPEND
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