Datasheet

ADP5065 Data Sheet
Rev. D | Page 20 of 40
BATTERY DETECTION
Battery Level Detection
The ADP5065 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 battery.
The sink phase (see Figure 32) sinks I
SINK
current from the
ISO_Bx/ BAT_SNS pins for a time, 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 or the
BAT_SNS pins for a time, t
BATOK
. If the 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.
Battery (ISO_Bx) Short Detection
A battery short occurs under a damaged battery condition or
when the battery protection circuitry is enabled.
On commencing trickle charging, the ADP5065 charger moni-
tors the battery voltage. If this battery voltage does not exceed
V
BAT_SHR
within the specified timeout period, t
BAT_SHR
, a fault is
declared and the charger is stopped by turning the battery
isolation FET off but the system voltage is maintained at
V
ISO_STRK
by the linear regulator.
The trickle charge branch is active during the battery short
scenario, and trickle charge current to the battery is maintained
until the 60 minute trickle charge mode timer expires.
After source phase, if the ISO_Bx or BAT_SNS level remains
below V
BATH
, either the battery voltage is low or the battery node
can be shorted. As a result of the battery voltage being low,
trickle charging mode is initiated (see Figure 33). If the
BAT_SNS level remains below V
BAT_SHR
after t
BAT_SHR
has elapsed,
the ADP5065 assumes that the battery node is shorted.
OPEN
ISO_Bx
SINK PHASE
LOGIC
STATUS
OPEN
OR
SHORT
t
BAT_OK
V
BATL
I
SINK
ISO_Bx
OPEN
OPEN
LOGIC
STATUS
SOURCE PHASE
t
BAT_OK
V
BATH
I
SOURCE
09370-032
Figure 32. Battery Detection Sequence
SHORT
SINK PHASE SOURCE PHASE TRICKLE CHARGE
ISO_Bx
SHORT
ISO_Bx
SHORT
ISO_Bx
LOGIC
STATUS
OPEN
OR
SHORT
t
BAT_OK
LOGIC
STATUS
SHORT
OR
LOW
BATTERY
t
BAT_OK
LOGIC
STATUS
SHORT
t
BAT_SHR
V
BATL
V
BATH
V
BAT_SHR
I
SOURCE
I
TRK_DEAD
I
SINK
09370-033
Figure 33. Battery Short Detection Sequence