Texas Instruments BQ7961-Q1 Series User Manual

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User's Guide
BQ7961x-Q1 Design Recommendations for High Voltage
Automotive BMS
Taylor Vogt
The BQ79616-Q1 provides high-accuracy cell voltage measurements for 6S to 16S battery modules in <200 µs.
The integrated front end filters enable the system to implement simple, low-cost, differential RC filters on the
cell input channels. The integrated, post-ADC, low-pass filters enable filtered, DC-like, voltage measurements for
better SOC calculation. This device supports autonomous internal cell balancing with temperature monitoring to
auto-pause and resume balancing to avoid an overtemperature condition.
The inclusion of the isolated, bidirectional, daisy chain ports supports both capacitor- and transformer-based
isolation, allowing the use of the most effective components for centralized or distribution architectures
commonly found in the xEV powertrain system. This device also includes eight GPIOs/auxiliary inputs that can
be used for NTC thermistor measurements.
1 NPN LDO Supply.....................................................................................................................................................................3
2 AVDD, CVDD outputs and DVDD, NEG5, REFHP and
3 OTP Programming..................................................................................................................................................................
4 Cell Voltage Sense (VCn) and Cell Balancing (CBn)...........................................................................................................
5 Bus Bar Support...................................................................................................................................................................
6 TSREF....................................................................................................................................................................................
7 General Purpose Input-Output (GPIO) Configurations.....................................................................................................
8 Base and Bridge Device Configuration..............................................................................................................................
9 Daisy-Chain Stack Configuration........................................................................................................................................29
10 Multi-Drop Configuration...................................................................................................................................................
11 Main ADC Digital LPF.........................................................................................................................................................
12 AUX Anti Aliasing Filter
13 Layout Guidelines...............................................................................................................................................................39
14 BCI Performance.................................................................................................................................................................42
15 Common and Differential Mode
16 Revision History.................................................................................................................................................................
Figure 1-1. Power Supply Schematic..........................................................................................................................................
Figure 2-1. Regulator Connection for Base Device.....................................................................................................................
Figure 4-1. Cell Voltage Monitoring.............................................................................................................................................
Figure 4-2. Internal CB Diagram (no adjacent cell balancing).....................................................................................................
Figure 4-3. Cell Balancing Resistor Example Calculation...........................................................................................................
Figure 4-4. Adjacent Cell Balancing..........................................................................................................................................
Figure 4-5. External FET Cell
Figure 4-6. Connecting Fewer Than 16 Cells............................................................................................................................
Figure 5-1. Alternative Bus Bar Connection to the Lower Stack
Figure 5-2. Example of BBP/BBN Connections at Different Module
Figure 5-3. BBP/N Connection With Bus Bar Connected in any Middle VC Channel ..............................................................
Figure 5-4. BBP/N Connection With Bus Bar Connected Above Top of a Module ...................................................................
Figure 5-5. Bus Bar Connected any Middle Individual VC Channel .........................................................................................
Figure 5-6. Bus Bar Connected Individual VC Channel Above the Top of a
SLVAE87A - DECEMBER 2020 - REVISED OCTOBER 2023
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ABSTRACT

Table of Contents

(AAF)...........................................................................................................................................38
Noise..............................................................................................................................42
List of Figures
Balancing....................................................................................................................................11
Copyright © 2023 Texas Instruments Incorporated
REFHM............................................................................................4
Device....................................................................................14
Size..................................................................................15
Module.................................................................19
BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS
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