BQ294502 Datasheet, PDF (8/18 Pages) Texas Instruments – Overvoltage Protection for 2-Series and 3-Series Cell Li-Ion Batteries

bq294502, bq294504, bq294512, bq294515
bq294522, bq294524, bq294532, bq294562
bq294572, bq294582, bq294592
SLUSAJ3C – SEPTEMBER 2011 – REVISED MAY 2012
APPLICATION INFORMATION
Pack +
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VCELL3
VCELL2
VCELL 1
RIN
bq2945xy
V3
RIN
CIN
OUT
V2
VDD
RIN
CIN
VSS
V1
PWRPAD
CIN
RVD
CVD
Figure 7. Application Configuration
Pack –
Changes to the ranges stated in Table 1 will impact the accuracy of the cell measurements. Figure 7 shows each
external component.
PARAMETER
Voltage monitor filter resistance
Voltage monitor filter capacitance
Supply voltage filter resistance
Supply voltage filter capacitance
Table 1. Parameters
External Component
RIN
CIN
RVD
CVD
MIN
NOM
MAX UNIT
900
1000
1100
Ω
0.01
0.1
µF
100
1K
Ω
0.1
µF
APPLICATION SCHEMATIC
Pack +
Pack +
VCELL3
VCELL2
VCELL 1
1k
1k ^0.1µF
bq2945xy
V3
OUT
V2
VDD
1k
0.1µF
VSS
V1
PWRPAD
0.1µF
100
0.1 µF
Pack –
Figure 8. 3-Series Cell Configuration with Fixed
Delay
VCELL2
VCELL 1
bq2945xy
V3
OUT
1k
V2
VDD
1k
0.1µF
VSS
V1
PWRPAD
0.1µF
100
0.1µF
Pack –
Figure 9. 2-Series Cell Configuration with Internal
Fixed Delay
CUSTOMER TEST MODE
Customer Test Mode (CTM) helps to reduce test time for checking the overvoltage delay timer parameter once
the circuit is implemented in the battery pack. To enter CTM, VDD should be set to at least 10 V higher than V3
(see Figure 10). The delay timer is greater than 10 ms, but considerably shorter than the timer delay in normal
operation. To exit Customer Test Mode, remove the VDD to VC3 voltage differential of 10 V so that the decrease
in this value automatically causes an exit.
CAUTION
Avoid exceeding any Absolute Maximum Voltages on any pins when placing the part
into Customer Test Mode. Also avoid exceeding Absolute Maximum Voltages for the
individual cell voltages (V3–V2), (V2–V1), and (V1–VSS). Stressing the pins beyond
the rated limits may cause permanent damage to the device.
8
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