ACT8810QJ62C-T View Datasheet(PDF) - Active-Semi, Inc
Part Name
Description
MFG CO.
'ACT8810QJ62C-T' PDF : 54 Pages View PDF
ACT8810
Rev 9, 15-Nov-12
ActivePathTM CHARGER
FUNCTIONAL DESCRIPTION CONT’D
Charger State-Machine
PRECONDITION State
A new charging cycle begins with the
PRECONDITION state, and operation continues in
this state until VBAT exceeds the Precondition
Threshold Voltage of 2.85V (typ). When operating
in PRECONDITION state, the cell is charged at a
reduced current, 12% of the programmed maximum
fast-charge constant current, ISET. Once VBAT
reaches the Precondition Threshold Voltage the
state machine jumps to the FAST-CHARGE state. If
VBAT does not reach the Precondition Threshold
Voltage before the Precondition Timeout period
tPRECONDITION expires, then a damaged cell is
detected and the state machine jumps to the
TIMEOUT-FAULT State. For the Precondition
Timeout period, see the Charging Safety Timers
section for more information.
FAST-CHARGE State
In FAST-CHARGE state, the ACT8810 charges at
the current programmed by RISET (see the Current
Limits and Charge Current Programming section for
more information). During a normal charge cycle
fast-charge continues in CC mode until VBAT
reaches the charge termination voltage (VTERM), at
which point the ACT8810 jumps to the TOP-OFF
state. If VBAT does not reach VTERM before the total
time out period expires then state-machine will jump
to the END-OF-CHARGE (EOC) state and will re-
initiate a new charge cycle after 2-4ms “relax”.
TOP-OFF State
In the TOP-OFF state, the cell charges in constant
voltage (CV) mode. In CV mode operation, the
charger regulates its output voltage to the 4.20V
(typ) charge termination voltage, and the charge
current is naturally reduced as the cell approaches
full charge. Charging continues until the charge
current drops to END-OF-CHARGE current
threshold, at which point the state machine jumps to
the END-OF-CHARGE (EOC) state. If the state-
machine does not jump out of the TOP-OFF state
before the Total-Charge Timeout period expires, the
state machine jumps to the EOC state and will re-
initiate a new charge cycle if VBAT falls below
termination voltage 170mv (typ). For more
information about the charge safety timers, see the
Charging Safety Times section.
END-OF-CHARGE State
In the End-of-Charge (EOC) state, the ACT8810
presents a high-impedance to the battery, allowing
the cell to “relax” and minimizes battery leakage
current. The ACT8810 continues to monitor the cell
voltage, so that it can re-initiate charging cycles
when VBAT drops to 170mV (typ) below the Charge
Termination Voltage.
SUSPEND State
In the SUSPEND state, ACT8810 disables the
charger but keeps other circuiting functional. Upon
exiting the SUSPEND State, the charge timer is
reset and the state machine jumps to
PRECONDITION state.
CHG_IN Bypass Capacitor Selection
CHG_IN is the power input for the ACT8810 battery
charger. The battery charger is automatically
enabled whenever a valid voltage is present on
CHG_IN. In most applications, CHG_IN is
connected to either a wall adapter or USB port.
Under normal operation, the input of the charger will
often be “hot-plugged” directly to a powered USB or
wall adapter cable, and supply voltage ringing and
overshoot may appear at the CHG_IN pin.
In most applications a high quality capacitor
connected from CHG_IN to GA, placed as close as
possible to the IC, is sufficient to absorb the energy.
Wall-adapter powered applications provide flexibility
in input capacitor selection, but the USB
specification presents limitations to input
capacitance selection. In order to meet both the
USB 2.0 and USB OTG (On The Go) specifications
while avoiding USB supply under-voltage conditions
resulting from the current limit slew rate
(100mA/µS) limitations of the USB bus, the
CHG_IN bypass capacitance value must to be
between 4.7µF and 10µF for the ACT8810.
Ceramic capacitors are often preferred for
bypassing applications due to their small size and
good surge current ratings, but care must be taken
in applications that can encounter hot plug
conditions as their very low ESR, in combination
with the inductance of the cable, can create a high-
Q filter that induces excessive ringing at the
CHG_IN pin. This ringing can couple to the output
and be mistaken as loop instability, or the ringing
may be large enough to damage the input itself.
Innovative PowerTM
ActivePMUTM and ActivePathTM are trademarks of Active-Semi.
I2CTM is a trademark of NXP.
- 51 -
www.active-semi.com
Copyright © 2012 Active-Semi, Inc.
Share Link: 
