More accurate battery gauging can be achieved by monitoring not only the battery voltage but also by tracking the charge that goes in and out of the battery. For applications requiring accurate battery gas gauging, the LTC2941 and LTC2942 coulomb counters are tiny and easy-to-use solutions. These feature-rich devices are small and integrated enough to fit easily into the latest handheld gadgets. The LTC2941 is a battery gas gauge device designed for use with single Li-Ion cells and other battery types with terminal voltages between 2.7V and 5.5V. A precision coulomb counter integrates current through a sense resistor between the battery’s positive terminal and the load or charger. The high side sense resistor avoids splitting the ground path in the application. The state of charge is continuously updated in an accumulated charge register (ACR) that can be read out via an SMBus/I2C interface. The LTC2941 also features programmable high and low thresholds for accumulated charge. If a 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 LTC2942 adds an ADC to the coulomb counter functionality of the LTC2941. The ADC measures battery voltage and chip temperature.
The document introduces the LTC2941 and LTC2942 as integrated coulomb counters designed to provide accurate battery gas gauging. Unlike methods that rely solely on voltage, these devices track charge flow through a sense resistor to determine remaining capacity, addressing inaccuracies caused by temperature and usage history.
Key features include an analog integrator for precise counting without external components (in the -1 versions) and optional integrated precision sense resistors. The LTC2942 adds an ADC to measure battery voltage and chip temperature with programmable thresholds.
| Operating Voltage Range | 2.7V to 5.5V |
|---|---|
| Package Type | 6-pin 2mm x 3mm DFN |
| Quiescent Current | 75µA |
| Charge Accuracy | Better than 1% |
| Temperature Error (LTC2942) | Typically below +2°C |
The LTC2942 adds an ADC to measure battery voltage and chip temperature, whereas the LTC2941 focuses on coulomb counting.
No, versions ending in '-1' include factory trimmed internal sense resistors.
It uses a continuous time analog integrator to measure charge based on current flow through a sense resistor.