bq24004
bq24005
bq24006
SLUS476B 鈥?DECEMBER 2000 鈥?REVISED MAY 2002
www.ti.com
Charge current feedback, applied through pin ISNS,
maintains regulation around a threshold of Vilim. The
following formula calculates the value of the sense
resistor:
V
(ilim)
R
(SNS)
+
I
(REG)
where I
(REG)
is the desired charging current.
The output stage is totem pole for the bq24004 and
bq24006 and open-drain for the bq24005. The following
tables summarize the operation of the three options:
Table 1. bq24004 (Single LED)
CHARGE STATE
Precharge
Fast charge
FAULT
Done (>90%)
Sleep-mode
APG/Therm invalid
Thermal shutdown
Battery absent
STAT1
ON (LOW)
ON (LOW)
Flashing (1 Hz, 50% duty cycle)
OFF (HIGH)
OFF (HIGH)
OFF (HIGH)
OFF (HIGH)
OFF (HIGH)
Voltage Monitoring and Regulation
Voltage regulation feedback is through pin VSENSE. This
input is tied directly to the positive side of the battery pack.
The bq2400x supports cells with either coke (8.2 V) or
graphite (8.4 V) anode. Pin VSEL selects the charge
regulation voltage.
VSEL State
(see Note)
Low
High
NOTE: VSEL should not be left floating.
CHARGE REGULATION
VOLTAGE
8.2 V
8.4 V
Table 2. bq24005 (2 Individual LEDs)
CHARGE STATE
Precharge
STAT1 (RED)
ON (LOW)
ON (LOW)
Flashing (1 Hz,
50% duty cycle)
OFF
OFF
OFF
OFF
STAT2
(GREEN)
OFF
OFF
OFF
ON (LOW)
OFF
OFF
OFF
OFF(1)
Charge Termination
The bq2400x continues with the charge cycle until
termination by one of the two possible termination
conditions:
Maximum Charge Time: The bq2400x sets the maximum
charge time through pin TMRSEL. The TMR SEL pin
allows the user to select between three different total
charge-time timers (3, 4, 5, or 6 hours). The charge timer
is initiated after the preconditioning phase of the charge
and is reset at the beginning of a new charge cycle. Note
that in the case of a fault condition, such as an out-of-range
signal on the APG/THERM input or a thermal shutdown,
the bq2400x suspends the timer.
TMRSEL STATE
Floating(1)
Low
High
CHARGE TIME
3 hours
6 hours
4.5 hours
Fast charge
FAULT
Done (>90%)
Sleep-mode
APG/Therm invalid
Thermal shutdown
Battery absent
OFF
(1) If thermistor is used, then the Green LED is off.
Table 3. bq24006 (Single Bicolor LED)
CHARGE STATE
Precharge
Fast charge
FAULT
Done (>90%)
Sleep-mode
APG/Therm
invalid
Thermal
shutdown
Battery absent
LED1 (RED)
ON (LOW)
ON (LOW)
ON (LOW)
OFF (HIGH)
OFF (HIGH)
OFF (HIGH)
OFF (HIGH)
OFF (HIGH)
LED2
(GREEN)
OFF (HIGH)
OFF (HIGH)
ON (LOW)
ON (LOW)
OFF (HIGH)
OFF (HIGH)
OFF (HIGH)
OFF (HIGH)(1)
APPARENT
COLOR
RED
RED
YELLOW
GREEN
OFF
OFF
OFF
OFF(1)
(1) To improve noise immunity, it is recommended that a minimum of
10 pF capacitor be tied to Vss on a floating pin.
Minimum Current: The bq2400x monitors the charging
current during the voltage regulation phase. The bq2400x
initiates a 22-minute timer once the current falls below the
taperdet trip threshold. Fast charge is terminated once the
22-minute timer expires.
(1) If thermistor is used, then the Green LED is off.
Charge Status Display
The three available options allow the user to configure the
charge status display for single LED (bq24004), two
individual LEDs (bq24005) or a bicolor LED (bq24006).
Thermal Shutdown
The bq2400x monitors the junction temperature T
J
of the
DIE and suspends charging if T
J
exceeds 165掳C.
Charging resumes when T
J
falls below 155掳C.
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