Breakthrough design enables high-accuracy, linear current measurement up to 100A by monitoring the voltage difference across copper traces on the circuit board21ic News Austriamicroelectronics announced the launch of a new reference design board that can measure current (with an accuracy error of only 1%) by monitoring the voltage difference of the copper traces on the circuit board.
Austriamicrosystems' new technology solution using the AS8510 data acquisition front-end helps battery management system (BMS) designers reduce bill-of-materials costs by eliminating the need for precision shunt resistors typically used in current-sensing applications. Precision resistors with low temperature drift typically cost about $1.50 each even in bulk.
In a battery management system (BMS), accurate current measurement is an essential function that facilitates monitoring the state of charge of the battery or knowing the remaining capacity. A new reference design board from austriamicrosystems provides a blueprint for current measurement in existing battery management systems. This reference design can also be used in electric vehicles, pedal assist vehicles and other applications requiring up to 40A current. Additionally, the design can be easily adapted to measure currents up to 100A using only the trace resistance of the copper on the board.
The AS8510 chosen for the new reference design by austriamicrosystems is an integrated data acquisition front end that provides two measurement channels with high sensitivity and accuracy. One of the channels measures the current through the voltage drop across a specific area of the copper on the board, and this 10mm area has a well-defined resistance value and temperature coefficient. The other channel is used to measure the temperature of the copper on the circuit board. This temperature measurement can be achieved directly by the AS8510, or an external temperature sensor can be used.
By using a compensation algorithm developed by austriamicrosystems, the AS8510 can eliminate the influence of changes in the resistance value of the copper sheet due to temperature changes. This means that the device can accurately measure changes in current (accurate ±1%).
Bernd Gessner, vice president and general manager of the automotive business at austriamicrosystems, said: "When equipped with a 100 µΩ resistor, the AS8510 can provide an extremely high current measurement accuracy of ±0.5%, and the measurement range is from a few milliamps to several thousand amperes. The new reference design from austriamicrosystems shows how the same device can measure current with almost the same accuracy when the resistor is removed."
"Designers of battery management systems (BMS) may face large fluctuations in ambient temperature when designing electric vehicles and electric pedal assist vehicles. Our reference design uses breakthrough temperature compensation technology to effectively reduce component costs , while meeting the high-precision measurement requirements of many applications."