LTC4099 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC4099' PDF : 36 Pages View PDF
LTC4099
Operation
via I2C (a disable followed by an enable). If the bad cell
indication returns, then the cell is definitively bad.
Bit 4 indicates that the battery charger is in thermal regula-
tion due to excessive LTC4099 junction temperature. Recall
that there are two I2C programmable junction temperature
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.
Table 7. NTC1, NTC0 Decode
THERMISTOR STATUS BIT DECODE
NTC1
NTC0
THERMISTOR STATUS
0
0
NO NTC FAULT
0
1
BATTERY TOO COLD
1
0
BATTERY TOO HOT
1
1
BATTERY OVERTEMPERATURE
Table 8. CHRGR1, CHRGR0 Decode
BATTERY CHARGER STATUS BIT DECODE
CHRGR1 CHRGR0
CHARGER STATUS
0
0
CHARGER OFF
0
1
CONSTANT-CURRENT
1
0
1
1
CONSTANT V, IBAT > C/x
CONSTANT V, IBAT < C/x
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 float voltage.
The CONSTANT V, IBAT > C/x bit indicates that the battery
charger has entered the float voltage phase of charging
(BAT at 4.1V or 4.2V), but that the charge current is still
above the C/x detection level programmed. The CONSTANT
V, IBAT <C/x bit indicates that the battery charge current
has dropped below the C/x detection level programmed,
and that charging is virtually complete. Note that if the
current limited USB compliant switching regulator is in
input current regulation, then the actual battery charge
current may be less than C/x due to insufficient available
power. If the LTC4099 is in input current limit, the charge
status bits will lock out (disallow) the state 1-1, indicating
that charging is complete. This feature prevents false full
capacity charge indications due to insufficient power to
the battery charger.
The status read from the LTC4099 is captured in one of
two ways. If an interrupt is currently pending, then the
available data represents the state of the LTC4099 at the
time the interrupt was generated. If no interrupt is pending,
then the data is captured when the LTC4099 acknowledges
its read address. In the case of a pending interrupt, fresh
data can be assured by taking two consecutive readings
of the status information and discarding the first set.
Shutdown Mode
The USB switching regulator is enabled whenever VBUS
is above VUVLO, greater than VDUVLO above BAT and the
LTC4099 is not in one of the two USB suspend modes
(500µA or 2.5mA). When power is available from both
the USB (VBUS) and WALL inputs, the auxiliary (WALL)
input is prioritized and the USB switching regulator is
disabled.
The battery charger will always start a charge cycle when
power
down
is detected at VBUS or
via a command from
WALL.
the I2C
It can only
port or by
be shut
normal
termination after a charge cycle.
The ideal diode is enabled at all times and cannot be
disabled.
4099fd
25
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