Featuring several innovations, the STC3115 is the latest adaptive fuel-gauge IC from ST Microelectronics and has already been selected by Samsung for some of its recent smartphones.
Battery charge indicators or fuel gauges are integrated in devices such as smartphones, laptops or digital cameras, delivering accurate ‘time-remaining’ predictions to enhance user experience, and can be critical in certain types of portable electronics such as medical devices. However, current technologies are susceptible to errors caused by battery aging, reduced charging efficiency, leakage, variations in system power demand, and temperature effects.
Until now, leading devices have used Coulomb counting to monitor energy entering and leaving the battery, and periodic voltage-mode state-of-charge measurements to adjust the Coulomb counter for accuracy. ST’s STC3115 uses both sets of measurements continuously, with OptimGauge, an adaptive algorithm that tracks the state of charge and corrects the battery model.
Key features of ST’s STC3115 fuel gauge ICs:
- Measures true initial battery open-circuit voltage and prevents measurement disruptions when connecting the charger or launching an app
- Patented charging inhibitor significantly improves accuracy
- Built-in aging and temperature compensation
- Voltage measurement accuracy is 0.25%
- Low-power mode reduces operating current to only 0.45µA while continuing to monitor the battery, and a 2µA standby mode
- Under-Voltage Lockout (UVLO) filter prevents short-term fluctuations in battery voltage from causing unwanted system resets
- Saves costs by operating directly from the battery voltage without requiring its own voltage regulator
- OptimGauge algorithm adjusts the battery charge/discharge model over the battery’s life
- Industry-standard I2C connection to application processor
- Programmable with different battery profiles at manufacture for flexibility
- Monitors batteries up to 4.5V
- Monitors multi-cell packs when used with TS941ILT low-power buffer
- Dedicated ‘battery-present’ input simplifies battery replacement
- Dedicated alarm output activated if battery voltage falls below threshold level