SLUUCJ0 November 2023 BQ76907
- 1
- Read This First
- 1 Introduction
- 2 Device Description
- 3 Device Configuration
- 4 Device Security
- 5 Measurement Subsystem
-
6 Protection
Subsystem
- 6.1 Protections Overview
- 6.2 Protection FET Drivers
- 6.3 Cell Overvoltage Protection
- 6.4 Cell Undervoltage Protection
- 6.5 Short Circuit in Discharge Protection
- 6.6 Overcurrent in Charge Protection
- 6.7 Overcurrent in Discharge 1 and 2 Protections
- 6.8 Current Protection Latch
- 6.9 CHG Detector
- 6.10 Overtemperature in Charge Protection
- 6.11 Overtemperature in Discharge Protection
- 6.12 Internal Overtemperature Protection
- 6.13 Undertemperature in Charge Protection
- 6.14 Undertemperature in Discharge Protection
- 6.15 Host Watchdog Protection
- 6.16 Cell Open Wire Detection
- 6.17 Voltage Reference Measurement Diagnostic Protection
- 6.18 VSS Measurement Diagnostic Protection
- 6.19 REGOUT Diagnostic Protection
- 6.20 LFO Oscillator Integrity Diagnostic Protection
- 6.21 Internal Factory Trim Diagnostic Protection
- 7 Device Status and Controls
- 8 Operational Modes
- 9 I2C Serial Communications
- 10Cell Balancing
-
11Commands and Subcommands
- 11.1 Direct Commands
- 11.2
Bit field Definitions for Direct Commands
- 11.2.1 Safety Alert A Register
- 11.2.2 Safety Status A Register
- 11.2.3 Safety Alert B Register
- 11.2.4 Safety Status B Register
- 11.2.5 Battery Status Register
- 11.2.6 Alarm Status Register
- 11.2.7 Alarm Raw Status Register
- 11.2.8 Alarm Enable Register
- 11.2.9 FET CONTROL Register
- 11.2.10 REGOUT CONTROL Register
- 11.2.11 DSG FET Driver PWM Control Register
- 11.2.12 CHG FET Driver PWM Control Register
- 11.3 Command-only Subcommands
- 11.4 Subcommands with Data
- 11.5 Bit field Definitions for Subcommands
-
12Data Memory
- 12.1 Calibration
- 12.2
Settings
- 12.2.1
Settings:Configuration
- 12.2.1.1 Settings:Configuration:Power Config
- 12.2.1.2 Settings:Configuration:REGOUT Config
- 12.2.1.3 Settings:Configuration:I2C Address
- 12.2.1.4 Settings:Configuration:I2C Config
- 12.2.1.5 Settings:Configuration:DA Config
- 12.2.1.6 Settings:Configuration:Vcell Mode
- 12.2.1.7 Settings:Configuration:Default Alarm Mask
- 12.2.1.8 Settings:Configuration:FET Options
- 12.2.1.9 Settings:Configuration:Charge Detector Time
- 12.2.2 Settings:Cell Balancing
- 12.2.3
Settings:Protection
- 12.2.3.1 Settings:Protection:Enabled Protections A
- 12.2.3.2 Settings:Protection:Enabled Protections B
- 12.2.3.3 Settings:Protection:DSG FET Protections A
- 12.2.3.4 Settings:Protection:CHG FET Protections A
- 12.2.3.5 Settings:Protection:Both FET Protections B
- 12.2.3.6 Settings:Protection:Body Diode Threshold
- 12.2.3.7 Settings:Protection:Cell Open Wire NORMAL Check Time
- 12.2.3.8 Settings:Protection:Cell Open Wire SLEEP Check Time
- 12.2.3.9 Settings:Protection:Host Watchdog Timeout
- 12.2.1
Settings:Configuration
- 12.3
Protections
- 12.3.1
Protections:Cell Voltage
- 12.3.1.1 Protections:Cell Voltage:Cell Undervoltage Protection Threshold
- 12.3.1.2 Protections:Cell Voltage:Cell Undervoltage Protection Delay
- 12.3.1.3 Protections:Cell Voltage:Cell Undervoltage Protection Recovery Hysteresis
- 12.3.1.4 Protections:Cell Voltage:Cell Overvoltage Protection Threshold
- 12.3.1.5 Protections:Cell Voltage:Cell Overvoltage Protection Delay
- 12.3.1.6 Protections:Cell Voltage:Cell Overvoltage Protection Recovery Hysteresis
- 12.3.2
Protections:Current
- 12.3.2.1 Protections:Current:Overcurrent in Charge Protection Threshold
- 12.3.2.2 Protections:Current:Overcurrent in Charge Protection Delay
- 12.3.2.3 Protections:Current:Overcurrent in Discharge 1 Protection Threshold
- 12.3.2.4 Protections:Current:Overcurrent in Discharge 1 Protection Delay
- 12.3.2.5 Protections:Current:Overcurrent in Discharge 2 Protection Threshold
- 12.3.2.6 Protections:Current:Overcurrent in Discharge 2 Protection Delay
- 12.3.2.7 Protections:Current:Short Circuit in Discharge Protection Threshold
- 12.3.2.8 Protections:Current:Short Circuit in Discharge Protection Delay
- 12.3.2.9 Protections:Current:Latch Limit
- 12.3.2.10 Protections:Current:Recovery Time
- 12.3.3
Protections:Temperature
- 12.3.3.1 Protections:Temperature:Overtemperature in Charge Protection Threshold
- 12.3.3.2 Protections:Temperature:Overtemperature in Charge Protection Delay
- 12.3.3.3 Protections:Temperature:Overtemperature in Charge Protection Recovery
- 12.3.3.4 Protections:Temperature:Undertemperature in Charge Protection Threshold
- 12.3.3.5 Protections:Temperature:Undertemperature in Charge Protection Delay
- 12.3.3.6 Protections:Temperature:Undertemperature in Charge Protection Recovery
- 12.3.3.7 Protections:Temperature:Overtemperature in Discharge Protection Threshold
- 12.3.3.8 Protections:Temperature:Overtemperature in Discharge Protection Delay
- 12.3.3.9 Protections:Temperature:Overtemperature in Discharge Protection Recovery
- 12.3.3.10 Protections:Temperature:Undertemperature in Discharge Protection Threshold
- 12.3.3.11 Protections:Temperature:Undertemperature in Discharge Protection Delay
- 12.3.3.12 Protections:Temperature:Undertemperature in Discharge Protection Recovery
- 12.3.3.13 Protections:Temperature:Internal Overtemperature Protection Threshold
- 12.3.3.14 Protections:Temperature:Internal Overtemperature Protection Delay
- 12.3.3.15 Protections:Temperature:Internal Overtemperature Protection Recovery
- 12.3.1
Protections:Cell Voltage
- 12.4 Power
- 12.5 Security
- 12.6 Data Memory Summary
- 13Revision History
5.1.2 Unused VC Cell Input Pins
If the BQ76907 device is used in a system with fewer than 7 series cells, specific cells must be used for connection to real cells, as shown in Table 5-8. Short out the unused cell inputs on the circuit board. The device only measures and reports those cells designated as real cells. For example, if only two cells are used (which requires cell-1 connected between VC1 ? VC0, and cell-2 connected between VC7 ? VC6), the 0x12 Cell 1 Voltage() command reports the lower cell voltage, while the 0x14 Cell 2 Voltage() command reports the upper cell voltage.
| Number of Cell Used (Vcell Mode setting) | Cell Connections | Shorted Cells |
|---|---|---|
| 0, 1, or 7 | VC7?VC6, VC6?VC5, VC5?VC4, VC4?VC3, VC3?VC2, VC2?VC1, VC1?VC0 | none |
| 6 | VC7?VC6, VC6?VC5, VC5?VC4, VC3?VC2, VC2?VC1, VC1?VC0 | VC4?VC3 |
| 5 | VC7?VC6, VC5?VC4, VC3?VC2, VC2?VC1, VC1?VC0 | VC6?VC5, VC4?VC3 |
| 4 | VC7?VC6, VC5?VC4, VC3?VC2, VC1?VC0 | VC6?VC5, VC4?VC3, VC2?VC1 |
| 3 | VC7?VC6, VC5?VC4, VC1?VC0 | VC6?VC5, VC4?VC3, VC3?VC2, VC2?VC1 |
| 2 | VC7?VC6, VC1?VC0 | VC6?VC5, VC5?VC4, VC4?VC3, VC3?VC2, VC2?VC1 |
Short the unused cell input pins to adjacent cell input pins, as shown in Figure 5-1.
It is also important to note that the range of voltages supported by the different VC pins differs depending on the pin. For example, pins VC7, VC6, and VC5 can only support measurements if their pin voltage is greater than or equal to 2 V. Thus if implementing a 2s system using the top and bottom cell input pins, the upper cell voltage is not measured correctly if the lower cell voltage drops below 2 V, because then VC6 is below 2 V.
Figure 5-1 Connecting an Unused Cell Input Pin
The Settings:Configuration:Vcell Mode data memory setting is used to specify which cell inputs are used for actual cells. The device uses this information to disable cell voltage protections associated with inputs which are not used. Voltage measurements are reported in 16-bit format (in units of mV) only for inputs used for real cells.