BQ2031PN-A5 Datasheet, PDF (6/19 Pages) Texas Instruments – Lead-Acid Fast-Charge IC

bq2031
Configuring Algorithm and Display
Modes
QSEL/LED3, DSEL/LED2, and TSEL/LED1 are bi-
directional pins with two functions; they are LED driver
pins as outputs and programming pins for the bq2031 as
inputs. The selection of pull-up, pull-down, or no pull re-
sistor programs the charging algorithm on QSEL and
TSEL per Table 1 and the display mode on DSEL per
Table 2. The bq2031 latches the program states when
any of the following events occurs:
1. VCC rises to a valid level.
2. The bq2031 leaves the Fault state.
3. The bq2031 detects battery insertion.
The LEDs go blank for approximately 750ms (typical)
while new programming data is latched.
For example, Figure 5 shows the bq2031 configured for
the Pulsed Current algorithm and display mode 2.
VCC
13
VCC
12
VSS
BAT +
RB1
2
FLOAT
BAT ^{3 RB3}
RB2
VSS
SNS ⁷
bq2031
BAT -
RSNS
FG203102.eps
Voltage and Current Monitoring
The bq2031 monitors battery pack voltage at the BAT
pin. A voltage divider between the positive and negative
terminals of the battery pack is used to present a scaled
battery pack voltage to the BAT pin and an appropriate
value for regulation of float (maintenance) voltage to the
FLOAT pin. The bq2031 also uses the voltage across a
Figure 6. Configuring the Battery Divider
sense resistor (RSNS) between the negative terminal
of the battery pack and ground to monitor current.
See Figure 6 for the configuration of this network.
VCC
LED2/DSEL
LED1/TSEL
VCC
VSS
COM
LED3/QSEL
bq2031
10K
16
15
13
12
10K
1K
1K
11
10
1K
10K
VSS
FG203103.eps
Figure 5. Configuring Charging Algorithm and Display Mode
6