24 January 2011
Analogue front ends for sensor systems ease the design process
In a move intended to ease the development process for sensor based systems, National Semiconductor has launched the first devices in a range of analogue front ends (afe) for sensor systems.
The parts, accompanied by a web based design tool and a development platform, are said to reduce the design cycle from, potentially, months to 'just minutes'.
Anita Ganti, director of National's precision systems business unit, said: "Designers have a complex task which involves a lot of research and optimisation. They need to choose a sensor, determine how it behaves over time and temperature, select components to drive the sensor and work out how the signal is amplified and converted. Then they have to layout a board and validate the design. We are looking to make this easier, so system designers can focus on differentiating their products."
Two parts have been launched initially. The LMP90100 is a multichannel 24bit afe which includes background calibration and diagnostics. The LMP91000 is a configurable potentiostat providing a signal path between a sensor and an a/d converter. These are accompanied by Webench Sensor AFE Designer, which is preloaded with specifications for a range of temperature, pressure and chemical sensors, and the development platform.
With a 24bit ?S a/d converter, the LMP90100 also features background calibration. "When collecting the sample," Ganti said, "the device also collects other data in the digital domain and use an integral state machine to calculate gain and offset."
According to Ganti, more products will be launched that work with different classes of sensor, including parts targeted at medical applications.
Meanwhile, the LMP91000 is targeted at chemical and gas sensing, working with three electrode gas sensors and two terminal oxygen sensors. Current is generated in proportion to gas concentration and this is converted to a voltage using a transimpedance amplifier with programmable gain. Its low power consumption, said to be less than 10µA, makes it suitable for use in battery powered applications.
Author
Graham Pitcher
Supporting Information
Websites
http://www.national.com
Companies
National Semiconductor
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