BQ2961_17 Datasheet, PDF (18/33 Pages) Texas Instruments – Overvoltage Protection for 2-Series, 3-Series, and 4-Series Cell Li-Ion Batteries with Regulated Output Supply

bq2961, bq2962
SLUSBU5D – NOVEMBER 2013 – REVISED JANUARY 2017
9 Application and Implementation
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NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The bq296xxx is a family of second-level protectors used for overvoltage protection of the battery pack in the
application. A regulated output is available to drive a small circuit with maximum I_REG loading. The device OUT
pin is active high, which drives a NMOS FET that connects the fuse to ground in the event of a fault condition.
This provides a shorted path to use the battery and/or charger power to blow the fuse and cut the power path.
9.2 Typical Application
Figure 13 shows the recommended reference design components.
100 Ÿ
VCELL3
VCELL2
VCELL1
1 NŸ
0.1 µF
1 NŸ
1 NŸ ^{0.1 µF}
0.1 µF
VDD
V3
bq2960
V2
OUT
REG
VSS
V1
REG_EN
PWPD
bq2960 REG out is controlled by MCU
10 M
(Optional)
Protector ^{Pack +}
FETs
5 (*)
External
Circuit
e.g., RTC
0.1 µF
0.47 µF
* can be removed if Vss will be
connected first during cell
connection
Pack ±
100 Ÿ
VCELL4
VCELL3
VCELL2
VCELL1
1 NŸ
1 NŸ ^{0.1 µF}
1 NŸ ^{0.1 µF}
1 NŸ ^{0.1 µF}
0.1 µF
VDD
V4 _bq2961
V3 ^bq2962
OUT
REG
VSS
V2
V1
PWPD
MCU
CTL
Protector ^{Pack +}
FETs
5 (*)
External
Circuit
e.g., RTC
0.1 µF
0.47 µF
* can be removed if Vss will be
connected first during cell
connection
Pack ±
Figure 16. Application Schematic
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9.2.1 Design Requirements
NOTE
Changes to the ranges stated in Table 4 will impact the accuracy of the cell
measurements.
PARAMETER
Voltage monitor filter resistance
Voltage monitor filter capacitance
Supply voltage filter resistance
Supply voltage filter capacitance
REG output capacitance
Table 4. Parameters
EXTERNAL COMPONENT
R_IN
C_IN
R_VD
C_VD
C_REG
MIN
900
0.01
0.1
—
0.47
NOM
1000
0.1
—
0.1
1
MAX
4700
1.0
1
1.0
—
UNIT
Ω
µF
KΩ
µF
µF
NOTE
The device is calibrated using an R_IN value = 1 kΩ. Using a value other than the
recommended value changes the accuracy of the cell voltage measurements and V_OV
trigger level.
18
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