Datasheet

Data Sheet ADP5065
Rev. D | Page 19 of 40
Safety Timer
If the watchdog timer (see the Watchdog Timer section for
more information) expires while in charger mode, the ADP5065
charger initiates the safety timer, t
SAFE
. If the processor has
programmed charging parameters by this time, the I
LIM
is set to
the default value. Charging continues for a period of t
SAFE
, then
the charger switches off and sets the CHARGER_STATUS register.
Charge Complete
The ADP5065 charger monitors the charging current while
in constant voltage fast charge mode. If the current falls
below I
END
and remains below I
END
for t
END
, charging stops
and the CHDONE flag is set. If the charging current falls below
I
END
for less than t
END
and then rises above I
END
again, the t
END
timer resets.
Recharge
After the detection of charge complete, and the cessation of
charging, the ADP5065 charger monitors the BAT_SNS pin as
the battery discharges through normal use. If the BAT_SNS pin
voltage falls to V
RCH
, the charger reactivates charging. Under
most circumstances, triggering the recharge threshold results in
the charger starting directly into fast charge constant voltage
mode.
Battery Charging Enable/Disable
The ADP5065 charging function can be disabled by setting the
I
2
C EN_CHG bit to low.
THERMAL MANAGEMENT
Isothermal Charging
To assist with the thermal management of the ADP5065
charger, the battery charger provides an isothermal charging
function. As the on-chip power dissipation and die temperature
increase, the ADP5065 charger monitors die temperature and
limits output current when the temperature reaches T
LIM
(typically at 115°C). The die temperature is maintained at T
LIM
through the control of the charging current into the battery. A
reduction in power dissipation or ambient temperature may
allow the charging current to return to its original value, and
the die temperature subsequently drops below T
LIM
. During
isothermal charging, the THERM_LIM flag is set to high.
Thermal Shutdown and Thermal Early Warning
The ADP5065 switching charger features a thermal shutdown
threshold detector. If the die temperature exceeds T
SD
, the
ADP5065 charger is disabled, and the TSD 140°C bit is set. The
ADP5065 charger can be reenabled when the die temperature
drops below the T
SD
falling limit and the TSD 140°C bit is reset.
To reset the TSD 140°C bit, write to the I
2
C Fault Register 0x0D
or cycle the power.
Before die temperature reaches T
SD
, the early warning bit is set if
T
SDL
is exceeded. This allows the system to accommodate power
consumption before thermal shutdown occurs.
Fault Recovery
Before performing the following operation, it is important to
ensure that the cause of the fault has been rectified.
To recover from a charger fault (when the CHARGER_STATUS
equals 110), cycle power on VINx or write high to reset the I
2
C
fault bits in the fault register.
BATTERY ISOLATION FET
The ADP5065 charger features an integrated battery isolation
FET for power path control. The battery isolation FET isolates a
deeply discharged Li-Ion cell from the system power supply in
both trickle and fast charge modes, thereby allowing the system
to be powered at all times.
When VINx is below V
VIN_OK
, the battery isolation FET is in full
conducting mode.
The battery isolation FET is off during trickle charge mode.
When the battery voltage exceeds V
TRK
, the battery isolation
FET switches to the system voltage regulation mode. During
system voltage regulation mode, the battery isolation FET
maintains the V
ISO_SFC
voltage on the ISO_Sx pins. When the
battery voltage exceeds V
ISO_SFC
, the battery isolation FET is in
full conducting mode.
The battery isolation FET supplements the battery to support
high current functions on the system power supply.
When voltage on ISO_Sx drops below ISO_Bx, the battery
isolation FET enters into full conducting mode.
When voltage on ISO_Sx rises above ISO_Bx, the isolation FET
enters regulating mode or full conduction mode, depending on the
Li-Ion cell voltage and the dc-to-dc charger mode.