SLUUCD5 January 2023 BQ27427
The BQ27427 battery fuel gauge accurately predicts the battery capacity and other operational characteristics of a single, Li-based, rechargeable cell. It can be interrogated by a system processor to provide cell information, such as state-of-charge (SOC).
Unlike some other Impedance Track™ fuel gauges, the BQ27427 cannot be programmed with specific battery chemistry profiles. Three pre-defined chemistry profiles (shown below) are available in the device memory. For many battery types and applications, these profiles are sufficient matches from a gauging perspective.
Chem ID | Voltage |
---|---|
3230 | 4.35 V (default) |
1202 | 4.2 V |
3142 | 4.4 V |
Information is accessed through a series of commands, called Standard Commands. Further capabilities are provided by the additional Extended Commands set. Both sets of commands, as indicated by the general format Command(), are used to read and write information contained within the control and status registers, as well as its data locations. Commands are sent from the system to the gauge using the I2C serial communications engine, and can be executed during application development, system manufacture, or end-equipment operation.
The key to the high-accuracy, fuel gauging prediction is Texas Instruments proprietary Impedance Track algorithm. This algorithm uses cell measurements, characteristics, and properties to create SOC predictions that can achieve high accuracy across a wide variety of operating conditions and over the lifetime of the battery.
The fuel gauge measures the charging and discharging of the battery by monitoring the voltage across a small-value, integrated sense resistor. Cell impedance is computed based on current, open-circuit voltage (OCV), and cell voltage under loading conditions.
The fuel gauge uses an integrated temperature sensor for estimating cell temperature. Alternatively, the system processor can provide temperature data for the fuel gauge.
To minimize power consumption, the fuel gauge has several power modes: INITIALIZATION, NORMAL, SLEEP, and SHUTDOWN. The fuel gauge passes automatically between these modes, depending upon the occurrence of specific events, though a system processor can initiate some of these modes directly.