Magnetic sensors modernise position sensing for the IoT era

7th September 2017
Posted By : Alice Matthews
Magnetic sensors modernise position sensing for the IoT era

Offering high power efficiency, flexible I2C configuration, and built-in tamper detection and temperature sensing, Silicon Labs brings Hall-effect sensing into the 21st century with a magnetic sensor portfolio. Silicon Labs’ new Si72xx portfolio includes what the company claims to be the most advanced, feature-rich magnetic sensors available today, outclassing reed switches and traditional Hall-effect devices in a wide range of open/close and position-sensing applications.

The Si72xx magnetic sensors provide solid-state reliability for white goods, flow meters, cordless power tools, wheel and dial-type controls for consumer electronics, industrial alarms, motor controls and door/window security applications. The sensors are AEC-Q100-qualified for automotive applications and designed to withstand harsh industrial environments.

Silicon Labs’ Si72xx sensors solve several tradeoffs in selecting the right magnetic sensing solution for power- and cost-sensitive applications. Reed switches consume very little power but are bulky and unreliable. While Hall-effect sensors offer solid-state reliability, they are more power hungry. Traditional Hall-effect designs are also stuck in the past, providing only a few of the programmable capabilities and advanced features offered by other modern sensor types used in IoT applications. Si72xx sensors address these needs by matching the power efficiency of reed switches with the reliability of Hall-effect sensors, while adding more advanced features, higher sensitivity and configurability.

Ultra-Low Power: Developers can finally add reliable Hall-effect-based sensors to battery-powered systems without impacting the system’s battery life. Operating below 100nA (sleep current) and less than 400nA for a 5Hz sampling rate, Si72xx sensors can help designs achieve multiyear and decade-long battery lifetimes, even when powered by very small batteries.

High Sensitivity: The outstanding sensitivity of Si72xx sensors (less than 1.1mT Bop, less than 30uT RMS noise, less than 0.1% linearity and 20mT/200mT ranges) enables developers to reduce the size of magnetics in their designs by 50 to 80% or extend sensing range by 2x or more.

Configurability: Si72xx sensors can easily be configured, measured and controlled over an I2C interface, providing greater flexibility during design and in the end product. Using an I2C interface dramatically reduces current for position-sensing applications by enabling the sensor to be queried as needed instead of continuously.

Advanced Features: Si72xx sensors include many useful built-in capabilities such as a tamper threshold feature that enables systems to detect attempts to bypass security. Most reed switch and Hall-effect sensor-based security systems can be defeated by a strong external magnetic field. The Si72xx sensors’ tamper detection technology detects anomalous magnetic fields, and a built-in self-test mode can be used to verify the sensor’s continued accurate operation in the field. Si72xx sensors also include a ±1°C accurate temperature sensor, eliminating the need for discrete temperature sensing, reducing system size and cost, and enhancing functionality.

The Si72xx sensor portfolio includes three families:

  • The Si720x family supports digital output switch and latch capabilities in a variety of sampling rates and sensitivities. These sensors are suitable for applications requiring a periodic on-off signal with the change of a magnetic field.
  • The Si721x family includes linear output devices for position-sensing applications that produce signals directly proportional to the strength of the magnetic field. These sensors support different gains and output types including analog, pulse-width modulation (PWM) and the SENT protocol for automotive communications.
  • The Si7210 family of I2C-configurable sensors supports all of the features and capabilities of the other two families while providing unmatched design flexibility and programmability.

“Nothing in the Hall-effect sensor market today can match the Si72xx portfolio’s combination of ultra-low power, high sensitivity, flexibility, configurability and features,” said Tom Pannell, Senior Marketing Director for IoT products at Silicon Labs. “Silicon Labs’ comprehensive portfolio enables developers to choose the right magnetic sensor type for their application needs, enabling them to design, test and deploy a wide range of sophisticated position-sensing products – better, faster, cheaper and with longer battery life.”

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