Datasheet

Functional Description
General Operation
The bq2050H determines battery capacity by moni
-
toring the amount of current input to or removed
from a rechargeable battery. The bq2050H meas
-
ures discharge and charge currents, measures bat
-
tery voltage, estimates self-discharge, monitors the
battery for low battery-voltage thresholds, and com
-
pensates for temperature and discharge rate. Cur
-
rent measurement is measured by monitoring the
voltage across a small-value series sense resistor be
-
tween the negative battery terminal and ground.
Scaled available energy is estimated using the re
-
maining average battery voltage during the dis
-
charge cycle and the remaining nominal available
capacity. The scaled available energy measurement
is corrected for environmental and operating condi
-
tions.
Figure 1 shows a typical battery pack application of the
bq2050H using the LED display capability as a charge-
state indicator. The bq2050H is configured to display
capacity in relative display mode. The relative display
mode uses the last measured discharge capacity of the
battery as the battery “full” reference. A push-button
display feature is available for momentarily enabling
the LED display.
The bq2050H monitors the charge and discharge cur
-
rents as a voltage across a sense resistor. (See R
S
in Fig
-
ure 1.) A filter between the negative battery terminal
and the SR pin is required.
3
bq2050H
FG2050H1.eps
CFC
SEG
5
/PROG
5
SEG
4
/PROG
4
SEG
3
/PROG
3
SEG
2
/PROG
2
SEG
1
/PROG
1
SR
DISP
SB
V
CC
REF
bq2050H
Power Gauge IC
LCOM
V
SS
RBI
HDQ
V
CC
C1
C2
Q1
ZVNL110A
R
1
R
S
RB
1
RB
2
See note 4
Load
Charger
1. Indicates optional.
2. Programming resistors and ESD-protection diodes are not shown.
3. RC on SR is required.
4. A series diode is required on RBI if the bottom series cell is used as the backup source.
If the cell is used, the backup capacitor is not required, and the anode is connected to the
positive terminal of the cell.
100K
PSTAT
Notes:
0.1µF
Figure 1. Battery Pack Application Diagram—LED Display