BQ24004_12 Datasheet, PDF (15/27 Pages) Texas Instruments – TWO-CELL Li-ION CHARGE MANAGEMENT IC

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DC+
V_CC
R_(SNS)
C1
V_CC
10 µF +
DC-
C2
0.1 µF
bq24004
bq24005
bq24006
SLUS476F – DECEMBER 2000 – REVISED MAY 2012
U1
1
N/C
20
N/C
2
IN
19
OUT
3
IN
18
OUT
4
VCC
17
VSENSE
5
ISNS
16
AGND
6
N/C
15
STAT2
7
14
APG/THM STAT1
8
EN
13
TMR SEL
9
VSEL
12
CR
10
GND
11
N/C
bq24005PWP
Figure 19. Current Sensing Circuit
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). 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
STAT1
ON (LOW)
ON (LOW)
Flashing (1 Hz, 50% duty cycle)
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