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Sensor interface IC suits battery management apps

Posted: 07 Apr 2010 ?? ?Print Version ?Bookmark and Share

Keywords:DAQ front-end? sensor interface? automotive?

AS8510 sensor interface

From austriamicrosystems comes a high-precision DAQ front-end IC for automotive battery current, voltage, temperature sense applications and in general for sensor interface applications where precise measurement of small signals close to ground is required.

The new flexible sensor interface IC, AS8510, offers advantages over alternative solutions, including being the first to feature a 16bit dual-channel ADC + PGA architecture with less than one LSB of offset and noise. The AS8510 allows systems tailored to individual needs making it well-suited for a wide range of present and future battery management applications. The AS8510 in combination with austriamicrosystems "System Basis Chip" and a microcontroller provides an entire battery sensor semiconductor solution for both high-side or low-side at a price below $2.8 in volume.

The AS8510 data acquisition front-end IC features two independent analog input channels with 16bit ADCs, each with individually programmable sampling rates. Each channel has a low-drift programmable gain amplifier for handling 160mV signals or 0V to 1V when by-passing PGA, thus battery currents from the mA range to the kA range can be measured from 100 shunt. A linear sigma delta architecture and wide range of sampling rates allows the AS8510 to provide flexible support of electric vehicle applications. The offset auto-zero feature (both channels) allows high accuracy measurements with low value shunt resistance (to 100) with negligible insertion loss. Also, various operating modes include low power standby with current monitoring for active wake-up.

The AS8510 operates with the current shunt sensor in a 12V system either at a battery's ground terminal or at the plus terminal in conjunction with dedicated level shift companion IC, or it can be used as a general purpose sensor interface for precise measurement of signals close to ground. Fully differential inputs allow the AS8510 to capture differential signals with 300mV of common mode above ground and 160mV below ground. The two-channel architecture enables digital error correction techniques like "delta by sigma" division or capture of bridge current/voltages with subsequent error correction in an external microcontroller. In addition, the AS8510 draws just 40?A in standby mode.

The AS8510 can be configured for differential simultaneous two-channel operation, or for multiplexing two single-ended channels in addition to one of the differential channels for sequential measurements. To measure voltage and current, the AS8510 also allows accurate temperature measurement from either the internal sensor or from an external temperature sensor, which may be powered by an on-chip 250?A current source. The AS8510 includes an internal precision reference, integrated digital low-pass filters, on-chip precision oscillators and a four-wire SPI interface.

The AS8510 is available in a SSOP20 package, operates from 3.3V, and has an ambient operating temperature range of -40C to +125C. An adapter board for quick start of AS8510 is available as well as an evaluation system for voltage, temperature and battery current measurement at 12V plus terminal.

- Paul Buckley
EE Times Europe

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