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ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - battery management Charge management Li-Ion SOIC 16 N Surface-mount
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time-out limit t
QT
(i.e., the battery has failed short), the
bq2954 enters the Fault state. Then t
QT
is set to 25% of
t
MTO
.IfV
MIN
is achieved before expiration of the time
limit, the bq2954 begins fast charging.
Once in the Fault state, the bq2954 waits until V
CC
is cy
-
cled or a new battery insertion is detected. It then starts a
new charge cycle and begins the qualification process again.
Charge Status Display
Charge status is indicated by the LED driver outputs
LED
1
–LED
2
. Three display modes (Tables 1– 3) are avail
-
able in the bq2954 and are selected by configuring pin
DSEL. Table 1 illustrates a normal fast charge cycle, Ta
-
ble 2 a recharge-after-fast-charge cycle, and Table 3 an ab
-
normal condition.
Configuring the Display Mode, I
FULL
/I
MIN
,
and I
SENSE
DSEL/LED
2
and CSEL/LED
1
are bi-directional pins
with two functions: as LED driver pins (output) and as
programming pins (input). The selection of pull-up,
pull-down, or no-resistor programs the display mode on
DSEL as shown in Tables 1 through 3. A pull-down or
no-resistor programs the current-sense mode on CSEL.
The bq2954 latches the programming data sensed on
the DSEL and CSEL input when V
CC
rises to a valid
level. The LEDs go blank for approximately 400ms (typi
-
cal) while new programming data are latched.
When fast charge reaches a condition where the charg
-
ing current drops below I
FULL
, the LED1 and LED2
outputs indicate a full-battery condition. Fast charge
terminates when the charging current drops below the
6
bq2954
GR295401.eps
V
BAT
I
BAT
V
REG
I
MAX
V
MIN
I
COND
I
FULL
I
MIN
Battery
Absent
Qualification
Charge
Complete
Low
Low
Low
Low
Low
Low
Low
High
Low
High
MTO
Fast Charge
Current
Regulate
LED1
LED2
LED1
LED2
LED1
LED2
CHG
BTST
CHG
BTST
High
Low
High
Low
High
Low
High
Low
High
High
High
Low
High
Low
High
Low
High
Low
High
Low
High
Low
High
Low
High
High
High
Low
High
Low
Low
High
Low
High
Low
High
High
Low
High
Low
Low
High
Low
High
Low
High
Low
Low
Low
Low
Mode 1
(DSEL = 0)
Mode 2
(DSEL = 1)
Mode 3
(DSEL = F)
Mode 1
and 2
Mode 3
Time
Voltage
Regulate
Current
Taper
I
FULL
Detect
Table 1. Normal Fast Charge Cycle