bq35100 Lithium Battery Fuel Gauge
Created: Nov 08, 2016
No description available.
One cause of battery damage is the prolonged usage without knowing its state-of-health. It is an assessment that reflects the condition of a battery in general. This state of health considers how much charge is accepted by the battery, the internal resistance of the battery, its current voltage and the rate of self-discharge of any battery in general. The reference design is an evaluation board for bq35100, a battery fuel gauge and end-of-service monitoring IC for non-rechargeable lithium primary batteries—without requiring forced discharge of the battery.
The bq35100 evaluation board power requirements are made simply due to its internal LDO regulation. The pin REGIN accepts any voltage level between 2.7V and 4.5V, which is optimum for single-cell Li-primary applications. The bq35100 measures the BAT input, which is scaled by the internal translation network, through the ADC. The translation gain function is determined by a calibration process. The bq35100 can measure temperature through an integrated temperature sensor or an external NTC thermistor (RT1). The integrating delta-sigma ADC in the bq35100 measures the discharge flow of the battery by measuring the voltage drop across resistor R18 between the SRP and SRN pins. The bq35100 can operate in three distinct modes: accumulator (ACC) mode, state-of-health (SOH) mode, and end-of-service mode (EOS). In accumulator mode, the bq35100 measures and updates cell voltage, cell temperature, and load current every 1sec. While on state-of-health mode which is suitable for determining SOH for lithium manganese dioxide (LiMnO2) chemistry, cell voltage and temperature are precisely measured immediately after the GE pin is asserted. For end-of-service, lithium thionyl Chloride (LiSOCl2) cells are much suited for this mode. In this mode, the EOS gauging algorithm uses voltage, current and temperature data to determine the resistance and the rate of its change. The host can read the gathered data through a 400-kHz I2C bus. An ALERT output is also available to interrupt the host, based on a variety of configurable options.
The bq35100 can also be put down to some basic applications like smart metering, door access control, smoke/gas detection, building automation, asset tracking, and internet of things (IoT).