Datasheet

Charge Status Display
Charge status is enunciated by the LED driver outputs
LED
1
–LED
3
. Three display modes are available in the
bq2054; the user selects a display mode by configuring
pin DSEL. Table 1 shows the three display modes.
The bq2054 does not distinguish between an over-
voltage fault and a “battery absent” condition. The
bq2054 enters the Fault state, enunciated by turning on
LED
3
, whenever the battery is absent. The bq2054,
therefore, gives an indication that the charger is on even
when no battery is in place to be charged.
Configuring the Display Mode and I
MIN
DSEL/LED
2
is a bi-directional pin with two functions; it
is an LED driver pin as an output and a programming
pin as an input. The selection of pull-up, pull-down, or
no pull resistor programs the display mode on DSEL per
Table 1. The bq2054 latches the programming data
sensed on the DSEL input when any one of the following
three events occurs:
1. V
CC
rises to a valid level.
2. The bq2054 leaves the Fault state.
3. The bq2054 detects battery insertion.
The LEDs go blank for approximately 750ms (typical)
while new programming data is latched.
5
bq2054
Mode Charge Action State LED
1
LED
2
LED
3
DSEL = 0
(Mode 1)
Battery absent or over-voltage fault Low Low High
Pre-charge qualification Flash Low Low
Fast charging High Low Low
Charge complete Low High Low
Charge pending (temperature out of range) X X Flash
Charging fault X X High
DSEL = 1
(Mode 2)
Battery absent or over-voltage fault Low Low High
Pre-charge qualification High High Low
Fast charge Low High Low
Charge complete High Low Low
Charge pending (temperature out of range) X X Flash
Charging fault X X High
DSEL = Float
(Mode 3)
Battery absent or over-voltage fault Low Low High
Pre-charge qualification Flash Flash Low
Fast charge: current regulation Low High Low
Fast charge: voltage regulation High High Low
Charge complete High Low Low
Charge pending (temperature out of range) X X Flash
Charging fault X X High
Note: 1 = V
CC
; 0 = V
SS
; X = LED state when fault occurred; Flash =
1
6
sec. low,
1
6
sec high.
Table 1. bq2054 Display Output Summary