Fuel gauge increases Li+ battery runtime
1 min read
Maxim Integrated Products has announced a fuel gauge which it claims increases Li+ battery runtime and provides the most accurate state of charge and time to empty in portable applications.
The MAX17047 fuel gauge is designed for single cell Li+ battery packs and features Maxim's new ModelGauge m3 algorithm. According to the power specialist, the device is the industry's only coulomb counting fuel gauge that doesn't suffer from abrupt corrections that can occur with traditional coulomb counter algorithms.
The IC is suitable for fuel gauging handheld single cell and multicell Li+ batteries in applications such as wireless handsets, smartphones, tablets and portable medical equipment.
ModelGauge m3 technology is designed to overcome the limitations of current techniques. Maxim states that it cancels offset accumulation error in the coulomb counter, while providing better short term accuracy than any only voltage based fuel gauge. The algorithm is said to continuously make tiny corrections over time and minimise abrupt corrections and reduce the sensitivity to current measurements a/d converter offset errors.
The MAX17047 automatically compensates for aging, temperature, and discharge rate and, according to Maxim, uses 75% less power than the competition. It adapts to changes in the battery over use and time and warns of abnormal battery conditions by providing two methods for reporting the age/health of the battery.
The IC provides measurements of current, voltage, and temperature. The temperature of the battery pack is measured using an external thermistor supported by ratiometric measurements on an auxiliary input. If the temperature information is available through some other means, then the system microcontroller is designed to also write the temperature directly to the IC. That eliminates the thermistor, plus a resistor and capacitor associated with this external thermistor network.
According to Maxim, the MAX17047 uses the lowest supply current in the industry (25µA, typ) and requires only one other resistor and three capacitors. Its measurement and power supply inputs connect directly to the battery pack, while the IC can be adapted for multicell series configuration, battery pack applications using an external buffer such as the MAX9910.
