Texas Instruments BQ7961-Q1 Series User Manual
Texas Instruments BQ7961-Q1 Series User Manual

Texas Instruments BQ7961-Q1 Series User Manual

Design recommendations for high voltage automotive bms
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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.
Supply.....................................................................................................................................................................3
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..............................................................................................................................
Configuration........................................................................................................................................29
10 Multi-Drop Configuration...................................................................................................................................................
11 Main ADC Digital LPF.........................................................................................................................................................
Guidelines...............................................................................................................................................................39
Performance.................................................................................................................................................................42
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 4-6. Connecting Fewer Than 16 Cells............................................................................................................................
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 .........................................................................................
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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  • Page 1: Table Of Contents

    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 Module..............19 SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 2 Table 12-1. AAF Settling Time..............................Trademarks All trademarks are the property of their respective owners. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 3: Npn Ldo Supply

    V BAT min   −   V LDOOIN max   +   V CE SAT   I LOAD max SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 4: Avdd, Cvdd Outputs And Dvdd, Neg5, Refhp And Refhm

    REFHM is the precision reference ground for the internal precision reference. Connect DVSS, CVSS, ADC_AVSS, REFHM, and AVSS externally. All VSS pins must not be left unconnected. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 5: Figure 2-1. Regulator Connection For Base Device

    Bypass the NEG5V pin to AVSS with a 0.1-µF/10-V capacitor. • Put all capacitors as close to pins as possible. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 6: Otp Programming

    Select the correct page and retry programming. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 7: Cell Voltage Sense (Vcn) And Cell Balancing (Cbn)

    BAL_CTRL2[AUTO_BAL] bit. To set up cell balancing control, refer to Set Up Cell Balancing section in the BQ79616-Q1 data sheet. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 8: Figure 4-2. Internal Cb Diagram (No Adjacent Cell Balancing)

    R DS ON   +   2 × R CB V BAT     −   R CB  =   DS ON I CB BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 9: Figure 4-3. Cell Balancing Resistor Example Calculation

    See Equation 4 to select the right adjacent cell balancing series resistor (R SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 10: Figure 4-4. Adjacent Cell Balancing

    MOSFET must be selected to provide sufficiently low R at half of the lowest battery voltage. DS(ON) BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 11: Figure 4-5. External Fet Cell Balancing

    VC0. See Figure 4-6 scenarios for more information on connecting fewer than 16 cells. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 12: Figure 4-6. Connecting Fewer Than 16 Cells

    Figure 4-6. Connecting Fewer Than 16 Cells BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 13: Bus Bar Support

    5-2, 4 x 12 cell can be monitored by 3 CMC without wasting any pins while connecting the bus bar to BBP/BBN. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 14: Figure 5-1. Alternative Bus Bar Connection To The Lower Stack

    Bus Bar Support www.ti.com Figure 5-1. Alternative Bus Bar Connection to the Lower Stack Device BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 15: Figure 5-2. Example Of Bbp/Bbn Connections At Different Module Size

    400-Ω filter resistor each on BBP/N pins and a 0.47-µF/16-V differential capacitor across BBP/N pins. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 16: Figure 5-3. Bbp/N Connection With Bus Bar Connected In Any Middle Vc Channel

    CB pin. This additional capacitor forms a complete capacitor ladder from all the cells in the module to the bus bar, allowing high spike voltage during hotplug to distributor across the capacitor ladder. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 17: Figure 5-4. Bbp/N Connection With Bus Bar Connected Above Top Of A Module

    SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 18: Figure 5-5. Bus Bar Connected Any Middle Individual Vc Channel

    It is used to distribute high voltage spikes with the same RC constant as the rest of the CB pins during a hotplug event. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 19: Figure 5-6. Bus Bar Connected Individual Vc Channel Above The Top Of A

    VC6 -VC7. CB7 is also floated. Each bus bar must be at least two channels apart. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 20: Figure 5-7. Two Bus Bars Connections Using Two Different Vc

    5-8. The first and the third bus bars are connected to each channels, VC4-VC3, and VC7-VC6, respectively. The second bus bar is connected to the dedicated bus bar pins, BBP/N. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 21: Figure 5-8. Multiple Bus Bar Connections Utilizing The Bbp/N Pins

    Bus Bar Support Figure 5-8. Multiple Bus Bar Connections Utilizing the BBP/N Pins SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 22: Tsref

    RAM as described in the data sheet. If the signal goes off the board, the input should be protected using a zener diode at the pin. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 23: Figure 7-1. Gpio Ratiometric Measurement

    SPI configuration replaces the GPIO pin configuration. Figure 7-2 shows an example connection of GPIO[7:4] for digital signaling or SPI mode. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 24: Figure 7-2. Example Spi Master Connections

    A single 4-channel 2:1 switch can be use to switch between SPI and thermistor input. Single switches available at TI and can be powered from CVDD as shown in Figure 7-3. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 25: Base And Bridge Device Configuration

    An overview of how a bridge device should be configured is shown in Figure 8-1. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 26: Figure 8-1. Communication With The Bridge Device

    SHUTDOWN ping through RX pin • a SLEEPtoACTIVE ping through RX pin • a HW_RESET ping through RX pin BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 27: Figure 8-3. Communication Pings

    SHUTDOWN tone through COMH/L • a HW_RESET tone through COMH/L Figure 8-4. Communication Tones SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 28: Figure 8-5. Diagram For Ping/Tone Propagation

    NFAULT is an active low fault indicator that, in the event of a fault, will pull low to signal to the host that a fault BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 29: Daisy-Chain Stack Configuration

    UART or SPI. A command is then moved up the chain of connected slave BQ79616-Q1 devices through COML and COMH pins vertically as described in Figure 9-2. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 30: Figure 9-1. Daisy Chain Structure With A Base Device

    Daisy-Chain Stack Configuration www.ti.com Figure 9-1. Daisy Chain Structure With a Base Device BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 31: Figure 9-2. Daisy Chain Structure With A Bridge

    800-V capacitor is needed. This configuration must be done on both the COMM± lines. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 32: Figure 9-3. Components Required For Cap Coupled Daisy Chain In The Same Pcb

    Components Required for cap-choke Daisy Chain with Cabling Figure 9-5. Components Required for Cap-Choke Daisy Chain With Cabling BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 33: Figure 9-6. Components Required For Transformer Coupled Daisy Chain

    Any capacitance present on the communication line can have an effect on the performance. All intentional and parasitic capacitance must be calculated and taken into effect. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 34: Figure 9-7. Example Of Changing Communication Direction In Daisy

    Power supplies OV, UV, oscillation detection • If OVUV protectors are enabled, cell OV and UV detection BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 35: Figure 9-8. Heartbeat Or Fault Tone Traveling Direction

    This is due to the re-clocking feature. Re-clocking allows for a longer daisy chain cable between board and also increased the number of stack-able devices in the system. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 36: Multi-Drop Configuration

    For more information, refer to the BQ79616-Q1 data sheet. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 37: Figure 10-1. Multi-Drop Configuration

    New recommendation to add 470 nF/16 V from CB16 to BAT for hotplug robustness not shown in above figure, see data sheet for details. Figure 10-1. Multi-Drop Configuration SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 38: Main Adc Digital Lpf

    Table 12-1. AAF Settling Time ADC_CONF1[AUX_SETTLE 1:0] Settling Time 4.3 ms 2.3 ms 1.3 ms 300 µs BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 39: Layout Guidelines

    SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 40: Figure 13-1. Grounding Layout Consideration

    If multiple devices are placed on the same PCB, each device should have its own ground plane with proper layout clearance. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 41: Figure 13-2. Separate Ground Plane Per Device On The Same Pcb

    1. Keep differential traces as short as possible and as straight as possible. Minimize turns and avoid any looping on the traces. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 42: Bci Performance

    Common mode noise goes out from both wires and returns back to the chassis through stray capacitance to ground. A Y capacitor is placed between the chassis as Figure 15-1 illustrates. BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 43: Figure 15-1. Xy Caps

    Device placement is important. The daisy-chain cable must not be resting on the bus bar or metal enclosure surface. SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 44: Revision History

    Updated the numbering format for tables, figures, and cross-references throughout the document ....• Updated document title ............................1 • Changed from application note to user's guide ....................BQ7961x-Q1 Design Recommendations for High Voltage Automotive BMS SLVAE87A – DECEMBER 2020 – REVISED OCTOBER 2023 Submit Document Feedback Copyright © 2023 Texas Instruments Incorporated...
  • Page 45 TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for TI products. TI objects to and rejects any additional or different terms you may have proposed. IMPORTANT NOTICE Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2023, Texas Instruments Incorporated...

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