Datasheet

R
(SNS)
+
V
(ilim)
I
(REG)
where I
(REG)
is the desired charging current.
U1
N/C N/C
1 20
IN OUT
2 19
IN OUT
3 18
VCC VSENSE
4 17
ISNS AGND
5 16
N/C STAT2
6 15
APG/THM STAT1
7 14
VSEL CR
9 12
EN TMR SEL
8 13
GND N/C
10 11
V
CC
C2
0.1 µF
R
(SNS)
C1
10 µF
+
DC-
DC+
V
CC
bq24005PWP
bq24004
bq24005
bq24006
www.ti.com SLUS476F –DECEMBER 2000–REVISED MAY 2012
Figure 19. Current Sensing Circuit
Charge current feedback, applied through pin ISNS, phase of the charge and is reset at the beginning of a
maintains regulation around a threshold of Vilim. The new charge cycle. Note that in the case of a fault
following formula calculates the value of the sense condition, such as an out-of-range signal on the
resistor: APG/THERM input or a thermal shutdown, the
bq2400x suspends the timer.
TMRSEL STATE CHARGE TIME
Floating
(1)
3 hours
Low 6 hours
High 4.5 hours
Voltage Monitoring and Regulation
(1)
To improve noise immunity, it is recommended that a minimum
of 10 pF capacitor be tied to Vss on a floating pin.
Voltage regulation feedback is through pin VSENSE.
This input is tied directly to the positive side of the
Minimum Current: The bq2400x monitors the
battery pack. The bq2400x supports cells with either
charging current during the voltage regulation phase.
coke (8.2 V) or graphite (8.4 V) anode. Pin VSEL
The bq2400x initiates a 22-minute timer once the
selects the charge regulation voltage.
current falls below the taperdet trip threshold. Fast
charge is terminated once the 22-minute timer
VSEL STATE CHARGE REGULATION
expires.
(see Note) VOLTAGE
Low 8.2 V
Charge Status Display
High 8.4 V
The three available options allow the user to
NOTE: VSEL should not be left floating.
configure the charge status display for single LED
(bq24004), two individual LEDs (bq24005) or a
Charge Termination
bicolor LED (bq24006). The output stage is totem
The bq2400x continues with the charge cycle until
pole for the bq24004 and bq24006 and open-drain for
termination by one of the two possible termination
the bq24005. The following tables summarize the
conditions:
operation of the three options:
Maximum Charge Time: The bq2400x sets the
Table 1. bq24004 (Single LED)
maximum charge time through pin TMRSEL. The
CHARGE STATE STAT1
TMR SEL pin allows the user to select between three
different total charge-time timers (3, 4, 5, or 6 hours).
Precharge ON (LOW)
The charge timer is initiated after the preconditioning
Fast charge ON (LOW)
FAULT Flashing (1 Hz, 50% duty cycle)
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Product Folder Link(s): bq24004 bq24005 bq24006