BQ24004 Datasheet, PDF (16/22 Pages) Texas Instruments – TWO-CELL Li-ION CHARGE MANAGEMENT IC FOR PDAs AND INTERNET APPLIANCES

bq24004
bq24005
bq24006
SLUS476B – DECEMBER 2000 – REVISED MAY 2002
Charge current feedback, applied through pin ISNS,
maintains regulation around a threshold of Vilim. The
following formula calculates the value of the sense
resistor:
R_(SNS)
+
V_(ilim)
I_(REG)
where I_(REG) is the desired charging current.
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)
CHARGE REGULATION
VOLTAGE
Low
8.2 V
High
8.4 V
NOTE: VSEL should not be left floating.
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)
CHARGE TIME
3 hours
Low
6 hours
High
4.5 hours
(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.
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).
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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)
Table 2. bq24005 (2 Individual LEDs)
CHARGE STATE
STAT1 (RED)
Precharge
ON (LOW)
Fast charge
ON (LOW)
FAULT
Flashing (1 Hz,
50% duty cycle)
Done (>90%)
OFF
Sleep-mode
OFF
APG/Therm invalid
OFF
Thermal shutdown
OFF
Battery absent
OFF
(1) If thermistor is used, then the Green LED is off.
STAT2
(GREEN)
OFF
OFF
OFF
ON (LOW)
OFF
OFF
OFF
OFF(1)
Table 3. bq24006 (Single Bicolor LED)
CHARGE STATE LED1 (RED)
LED2
(GREEN)
APPARENT
COLOR
Precharge
ON (LOW) OFF (HIGH)
RED
Fast charge
ON (LOW) OFF (HIGH)
RED
FAULT
ON (LOW) ON (LOW)
YELLOW
Done (>90%)
OFF (HIGH) ON (LOW)
GREEN
Sleep-mode
OFF (HIGH) OFF (HIGH)
OFF
APG/Therm
invalid
OFF (HIGH) OFF (HIGH)
OFF
Thermal
shutdown
Battery absent
OFF (HIGH) OFF (HIGH)
OFF (HIGH) OFF (HIGH)(1)
OFF
OFF(1)
(1) If thermistor is used, then the Green LED is off.
Thermal Shutdown
The bq2400x monitors the junction temperature T_J of the
DIE and suspends charging if T_J exceeds 165°C.
Charging resumes when T_J falls below 155°C.
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