LTC4099 Linear Technology Corporation, LTC4099 Datasheet - Page 24

• Manufacturer Part Number: LTC4099
• Description: I2C Controlled USB Power Manager/Charger
• Manufacturer: Linear Technology Corporation

www.DataSheet4U.com
as it can prevent the battery charger from bringing up
the battery voltage. Without the ability to address the I
port, only a low voltage on DV
its default state and re-enable charging.
The ENABLE_BATTERY_CONDITIONER bit enables the
automatic battery load circuit in the event of simultaneously
high battery voltage and temperature. See the Overtem-
perature Battery Conditioner section.
The V
LTC4099’s battery charger. A 1 in this bit position changes
the charger from the default fl oat voltage value of 4.100V
to the higher 4.200V level.
The T
charger junction thermal regulation temperature from its
default value of 105°C to a lower setting of 85°C. This may
be used to reduce heat in highly thermally compromised
systems. In general, the high effi ciency charging system
of the LTC4099 will keep the junction temperature low
enough to avoid junction thermal regulation.
The third and fi nal byte of input data at sub address 0x02
is the mask register. The mask register determines which
status change events or categories will be allowed to gener-
ate an interrupt. A 1 written to a given position in the mask
register allows status change in that category to generate
an interrupt. A zero in a given position in the mask register
prohibits the generation of an interrupt. The start-up state
of the LTC4099 is all zeros for this register indicating that
no interrupts will be generated without explicit request via
the I
Output Data
One status byte may be read from the LTC4099. Table 6
represents the status byte information. A 1 read back in
any of the bit positions indicates that the condition is true.
For example, 1s read back from bits 7 and 2 indicate that
power is available at V
thermistor has halted charging due to an undertemperature
condition at the battery.
Bit 7 in the status byte indicates the presence of power
at V
from the undervoltage lockout circuit on V
by the electrical parameters V
LTC4099
OPERATION
24
BUS
2
REG
C port. See the Interrupt Generation section.
FLOAT
. Criteria for determining this status bit is derived
= 85°C control bit changes the LTC4099’s battery
= 4.2V bit controls the fi nal fl oat voltage of the
BUS
, and that the battery charger’s
UVLO
CC
will clear the I
and V
DUVLO
BUS
and is given
.
2
C port to
2
C
Bit 6 indicates the presence of voltage available at the WALL
pin and is derived from the WALL undervoltage lockout
circuit. Like the V
voltage detection level given by the electrical parameter
V
Both of the conditions must be met for bit 6 to indicate
the presence of power at WALL.
Bit 5 indicates that the battery has been below the pre-
charge threshold level of approximately 2.85V for more
than one-half hour while the charger was attempting to
charge. When this occurs, it is usually the result of a de-
fective cell. However, in some cases a bad cell indication
may be caused by system load prioritization over battery
charging. System software can test for this by forcing a
reduction of system load and restarting the battery charger
via I
indication returns, then the cell is defi nitively bad.
Bit 4 indicates that the battery charger is in thermal regula-
tion due to excessive LTC4099 junction temperature. Recall
that there are two I
settings available at which to regulate, 85°C and 105°C.
Bit 4 indicates thermal regulation at whichever setting is
chosen.
Bits 3 and 2 indicate the status of the thermistor measure-
ment circuit and are decoded in Table 7. The BATTERY
TOO COLD and BATTERY TOO HOT states indicate that
the thermistor temperature is out of range (either below
0°C or above 45°C for a curve 2 thermistor) and that
charging has paused until a return to valid temperature.
The BATTERY OVERTEMPERATURE state indicates that
the battery’s thermistor has reached a critical temperature
(above 60°C for a curve 2 thermistor) and that long term
battery capacity may be seriously compromised if the
condition persists.
Bits 1 and 0 indicate the status of the battery charger, and
are decoded into one of four possible battery charger states
in Table 8. The constant-current state indicates that the
battery charger is attempting to charge with all available
current up to the constant-current level programmed,
and that the battery has not yet reached the fl oat voltage.
The CONSTANT V, I
charger has entered the fl oat voltage phase of charging
WALL
2
C (a disable followed by an enable). If the bad cell
, as well as a level relative to BAT given by ΔV
BUS
2
C programmable junction temperature
BAT
pin, this pin has both an absolute
> C/x bit indicates that the battery
WALL
4099f
.