ZHCSVT2A April 2022 – April 2024 BQ76922
PRODUCTION DATA
- 1
- 1 特性
- 2 应用
- 3 说明
- 4 Device Comparison Table
- 5 Pin Configuration and Functions
-
6 Specifications
- 6.1 Absolute Maximum Ratings
- 6.2 ESD Ratings
- 6.3 Recommended Operating Conditions
- 6.4 Thermal Information BQ76922
- 6.5 Supply Current
- 6.6 Digital I/O
- 6.7 LD Pin
- 6.8 Precharge (PCHG) and Predischarge (PDSG) FET Drive
- 6.9 FUSE Pin Functionality
- 6.10 REG18 LDO
- 6.11 REG0 Pre-regulator
- 6.12 REG1 LDO
- 6.13 Voltage References
- 6.14 Coulomb Counter
- 6.15 Coulomb Counter Digital Filter (CC1)
- 6.16 Current Measurement Digital Filter (CC2)
- 6.17 Current Wake Detector
- 6.18 Analog-to-Digital Converter
- 6.19 Cell Balancing
- 6.20 Cell Open Wire Detector
- 6.21 Internal Temperature Sensor
- 6.22 Thermistor Measurement
- 6.23 Internal Oscillators
- 6.24 High-side NFET Drivers
- 6.25 Comparator-Based Protection Subsystem
- 6.26 Timing Requirements – I2C Interface, 100kHz Mode
- 6.27 Timing Requirements – I2C Interface, 400kHz Mode
- 6.28 Timing Requirements – HDQ Interface
- 6.29 Interface Timing Diagrams
- 6.30 Typical Characteristics
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3 Diagnostics
- 7.4 Device Configuration
- 7.5
Measurement Subsystem
- 7.5.1 Voltage Measurement
- 7.5.2 General Purpose ADCIN Functionality
- 7.5.3 Coulomb Counter and Digital Filters
- 7.5.4 Synchronized Voltage and Current Measurement
- 7.5.5 Internal Temperature Measurement
- 7.5.6 Thermistor Temperature Measurement
- 7.5.7 Factory Trim of Voltage ADC
- 7.5.8 Voltage Calibration (ADC Measurements)
- 7.5.9 Voltage Calibration (COV and CUV Protections)
- 7.5.10 Current Calibration
- 7.5.11 Temperature Calibration
- 7.6 Primary and Secondary Protection Subsystems
- 7.7
Device
Hardware Features
- 7.7.1 Voltage References
- 7.7.2 ADC Multiplexer
- 7.7.3 LDOs
- 7.7.4 Standalone Versus Host Interface
- 7.7.5 Multifunction Pin Controls
- 7.7.6 RST_SHUT Pin Operation
- 7.7.7 CFETOFF, DFETOFF, and BOTHOFF Pin Functionality
- 7.7.8 ALERT Pin Operation
- 7.7.9 Fuse Drive
- 7.7.10 Cell Open Wire
- 7.7.11 Low Frequency Oscillator
- 7.7.12 High Frequency Oscillator
- 7.8 Device Functional Modes
- 7.9 Serial Communications Interface
- 7.10 Cell Balancing
- 8 Application and Implementation
- 9 Power Supply Requirements
- 10Layout
- 11Device and Documentation Support
- 12Revision History
- 13Mechanical, Packaging, Orderable Information
7.5.6 Thermistor Temperature Measurement
The BQ76922 device includes an on-chip temperature measurement and can also support up to five external thermistors on multifunction pins (TS1, TS2, CFETOFF, DFETOFF, and ALERT). The device includes an internal pullup resistor to bias a thermistor during measurement.
The internal pullup resistor has two options which can set the pullup resistor to either 18kΩ or 180kΩ (or none at all). The 18kΩ option is intended for use with thermistors such as the Semitec 103AT, which has 10kΩ resistance at room temperature. The 180-kΩ is intended for use with higher resistance thermistors such as the Semitec 204AP-2, which has 200kΩ resistance at room temperature. The resistor values are measured during factory production and stored within the device for use during temperature calculation. The individual pin configuration registers determine which pin is used for a thermistor measurement, what value of pullup resistor is used, as well as whether the thermistor measurement is used for a cell or FET temperature reading.
Figure 7-3 External
Thermistor BiasingIn order to provide a high precision temperature result, the device uses the same 1.8V 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. The device processes the digitized thermistor voltage to calculate the temperature based on multiorder polynomials, which can be programmed by the user based on the specific thermistor selected.