Datasheet

ADP5061 Data Sheet
Rev. C | Page 20 of 44
THERMAL MANAGEMENT
Isothermal Charging
The ADP5061 includes a thermal feedback loop that limits the
charge current when the die temperature exceeds T
LIM
(typically
115°C). As the on-chip power dissipation and die temperature
increase, the charge current is automatically reduced to maintain
the die temperature within the recommended range. As the die
temperature decreases due to lower on-chip power dissipation
or ambient temperature, the charge current returns to the pro-
grammed level. During isothermal charging, the THERM_LIM
I
2
C flag is set to high.
This thermal feedback control loop allows the user to set the
programmed charge current based on typical rather than worst
case conditions.
The ADP5061 does not include a thermal feedback loop to limit
ISO_Sx load current in LDO mode. If the power dissipated on
chip during LDO mode causes the die temperature to exceed
130°C, an interrupt is generated. If the die temperature
continues to rise beyond 140°C, the device enters into thermal
shutdown.
Thermal Shutdown and Thermal Early Warning
The ADP5061 charger features a thermal shutdown threshold
detector. If the die temperature exceeds T
SD
, the ADP5061
charger is disabled, and the TSD 140°C bit is set. The ADP5061
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 =
110), cycle power on VINx or write high to reset the I
2
C fault
bits in the fault register.
BATTERY ISOLATION FET
The ADP5061 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 linear charger mode.
BATTERY DETECTION
Battery Voltage Level Detection
The ADP5061 charger features a battery detection mechanism to
detect an absent battery. The charger actively sinks and sources
current into the ISO_Bx/BAT_SNS node, and voltage vs. time is
detected. The sink phase is used to detect a charged battery,
whereas the source phase is used to detect a discharged batter y.
The sink phase (see Figure 30) sinks I
SINK
current from the
ISO_Bx/ BAT_SNS pins for a time period, t
BATOK
. If the
BAT_SNS pin is below V
BATL
when the t
BATOK
timer expires, the
charger assumes no battery is present, and starts the source phase.
If the BAT_SNS exceeds the V
BATL
voltage when the t
BATOK
timer
expires, the charger assumes the battery is present and begins a
new charge cycle.
The source phase sources I
SOURCE
current to ISO_Bx and the
BAT_SNS pin for a time period, t
BATOK
. If BAT_SNS pin exceeds
V
BATH
before the t
BATOK
timer expires, the charger assumes that
no battery is present. If the BAT_SNS does not exceed the V
BATH
voltage when the t
BATOK
timer expires, the charger assumes that a
battery is present and begins a new charge cycle.