Datasheet
Starting A Charge Cycle
Either of two events starts a charge cycle (see Figure 4):
1.Applicationofpowerto V
CC
or
2. Voltage at the BAT pin falling through the maximum
cell voltage V
MCV
where
V
MCV
= 2V ±5%.
If the battery is within the configured temperature and
voltage limits, the IC begins fast charge. The valid
battery voltage range is V
LBAT
<V
BAT
<V
MCV,
where
V
LBAT
= 0.175 ∗ V
CC
±20%
The valid temperature range is V
TS
>V
HTF
where
V
HTF
= 0.6 ∗ V
CC
±5%.
If V
BAT
≤ V
LBAT
or V
TS
≤ V
HTF
, the IC enters the charge-
pending state. In this state pulse trickle charge is
applied to the battery and the LED flashes until the
voltage and temperature come into the allowed fast
charge range or V
BAT
rises above V
MCV
. Anytime V
BAT
≥ V
MCV
, the IC enters the Charge Complete/Battery
Absent state. In this state the LED is off and trickle
charge is applied to the battery until the next new
charge cycle begins.
Fast charge continues until termination by one or more of
the five possibleterminationconditions:
n
Peak voltage detection (PVD)
n
Negative delta voltage (-
∆
V)
n
Maximum voltage
n
Maximum temperature
n
Maximum time
4
Corresponding
Fast-Charge
Rate TM Termination
Typical
Fast-
Charge
Time Limits
(minutes)
Typical PVD
and -
∆
V
Hold-Off
Time (seconds)
Pulse-
Trickle
Rate
Pulse-
Trickle
Pulse Width
(ms)
Maximum
Synchronized
Sampling
Period
(seconds)
C/2 Mid PVD 160 300 C/32 73 18.7
1C Low PVD 80 150 C/32 37 18.7
2C High -
∆
V 40 75 C/32 18 9.4
Notes: Typical conditions = 25°C, V
CC
= 5.0V
Mid = 0.5
*
V
CC
±0.5V
Tolerance on all timing is ±12%.
Table 1. Fast-Charge Safety Time/Hold-Off Table
bq2002C
TD2002C1.eps
Fast ChargingV
CC
= 0 Fast Charging
CC Output
LED
Charge initiated by application of power
Charge initiated by battery replacement
Pulse-Trickle
See
Table 1
1s
Figure 4. Charge Cycle Phases