Datasheet

Data Sheet ADP5062
Rev. B | Page 21 of 44
THERMAL MANAGEMENT
Isothermal Charging
The ADP5062 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 ADP5062 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 thermal shutdown.
Thermal Shutdown and Thermal Early Warning
The ADP5062 charger features a thermal shutdown threshold
detector. If the die temperature exceeds T
SD
, the ADP5062 charger
is disabled, and the TSD 140°C bit is set. The ADP5062 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, Register Address 0x0D
(Bit 0) or cycle the power.
Before the 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 CHARGER_STATUS[2:0] =
110), cycle power on VINx or write high to reset the I
2
C fault bits
in the fault register (Register Address 0x0D).
BATTERY ISOLATION FET
The ADP5062 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_RISE
, 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_DEAD
, the battery iso-
lation 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 the
voltage on ISO_Sx drops below V
ISO_Bx
, the battery isolation FET
enters into full conducting mode. When voltage on ISO_Sx
rises above V
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 ADP5062 charger features a battery detection mechanism to
detect an absent battery. The charger actively sinks and sources
current into the ISO_Bx 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 battery.
The sink phase (see Figure 30) sinks I
SINK
current from the ISO_Bx
pins for a time period, t
BATOK
. If ISO_Bx is below V
BATL
when the
t
BATOK
timer expires, the charger assumes no battery is present and
starts the source phase. If the ISO_Bx pin 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 the ISO_Bx pins for
a time period, t
BATOK
. If If ISO_Bx exceeds V
BATH
before the t
BATOK
timer expires, the charger assumes that no battery is present. If
the ISO_Bx pin 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.