Linear Technology/Analog Devices’ LTC2941, LTC2942, LTC2943, and LTC2944 are battery fuel gauge devices. These devices measure battery charge state, battery voltage, and chip temperature in handheld PC and portable product applications. Their operating range is perfectly suited for single-cell Li-Ion or multi-chemistry batteries. A precision coulomb counter integrates current through a sense resistor between the battery’s positive terminal and the load or charger. Battery voltage and on-chip temperatures are measured with an internal 14-bit No Latency ΔΣ™ ADC. The three measured quantities (charge, voltage, and temperature) are stored in internal registers accessible via the onboard SMBus/I²C interface. The LTC2941 and LTC2942 feature programmable high and low thresholds for all three measured quantities, whereas the LTC2943 and LTC2944 feature them for all four measured quantities. If a programmed threshold is exceeded, the device communicates an alert using either the SMBus alert protocol or by setting a flag in the internal status register. The LTC2941, LTC2942, LTC2943, and LTC2944 require only a single low value sense resistor to set the measured current range. They have been designed for low power battery applications such as smart phones, cameras, and GPS.