BQ2002ESNTR Datasheet, PDF (4/15 Pages) Texas Instruments – NiCd/NiMH Fast-Charge Management ICs

bq2002E/G
VCC = 0
Fast Charging
CC Output
Top-Off
(optional)
73ms
Pulse-Trickle
Fast Charging
See Table 1
LED
1.17s
1.17s
Charge initiated by application of power
Charge initiated by battery replacement
Figure 4. Charge Cycle Phases
TD2002EG.eps
A ground-referenced negative temperature coefficient ther-
mistor placed near the battery may be used as a low-cost
temperature-to-voltage transducer. The temperature
sense voltage input at TS is developed using a resistor-
thermistor network between VCC and VSS. See Figure 1.
Starting A Charge Cycle
Either of two events starts a charge cycle (see Figure 4):
1. Application of power to VCC or
2. Voltage at the BAT pin falling through the maximum
cell voltage VMCV where
VMCV = 2V ±5%.
If the battery is within the configured temperature and
voltage limits, the IC begins fast charge. The valid bat-
tery voltage range is VLBAT < VBAT < VMCV, where
Table 1. Fast-Charge Safety Time/Hold-Off/Top-Off Table
Typical Fast-
Charge and
Maximum
Top-Off
Synchro-
Corre-
Time Limits
Typical PVD
Pulse- nized
sponding
(minutes)
and -∆V
Pulse- Trickle Sampling
Fast-Charge
Hold-Off Time Top-Off Trickle Width Period
Rate
TM Termination bq2002E bq2002G (seconds)
Rate
Rate (ms) (seconds)
C/2
Mid
PVD
200
160
300
Disabled C/32
73
18.7
1C
Low
PVD
80
80
150
C/16
C/32
37
18.7
2C
High
-∆V
40
40
75
Disabled C/32
18
9.4
Notes:
Typical conditions = 25°C, VCC = 5.0V
Mid = 0.5 _* VCC ± 0.5V
Tolerance on all timing is ± 12%.
4