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
5.4 Thermistor Temperature Measurement
The BQ76907 device includes an on-chip temperature measurement and can also support measurement of an external thermistor on the TS pin. The device includes an internal trimmed 20-kΩ pullup resistor to bias the thermistor during measurement. The TS pin can be selected for thermistor measurement or general purpose ADCIN measurement using the Settings:Configuration:DA Config[TSMODE] data memory setting.
When the pin is selected for thermistor measurement, the internal pullup resistor is used to bias the pin during the measurement. To provide a high precision result, the device uses the same 1.8 V internal LDO voltage for the ADC reference as is used for biasing the thermistor pullup resistor, thereby implementing a ratiometric measurement that removes the error contribution from the LDO voltage level. Because the pullup resistor is only enabled during the pin measurement, it is recommended to limit the capacitance at this node to less than 4 nF to reduce the effect of incomplete settling when the pullup resistor is biased.
If the pin is selected for general purpose ADCIN measurement, the pullup resistor is not enabled during measurement, and the ADC uses VREF1 for its reference when measuring the pin.
The data is reported using the TS Measurement() command, in units of 16-bit ADC counts. The full-scale digital value reflects an analog input level of its reference × 5 / 3. So when the TS pin is measuring a thermistor in ratiometric mode using the 1.8V internal regulator for its reference, the 16-bit LSB is 1.8 V × 5 / 3 / 32768 ? 92 μV. When the TS pin is measuring in ADCIN mode using the VREF1 reference, the 16-bit LSB is 1.1962 V × 5 / 3 / 32768 ? 61 μV. The processing performed on the ADC data before reporting is shown below, using the Calibration:Temperature:TS Offset data memory parameter.
