Melexis – Current Sensing Made Easy MLX91210 – Integrated, Calibrated and Compact

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Managing power properly to ensure that power-oriented systems operate safely and efficiently, as well as providing telemetry to system controllers, is increasing in importance due to environmental issues and rising energy costs. Improving the quality of data can only be achieved by continuing to develop higher performance and convenient current sensors.

Conventional approaches to current sensing include shunt resistors which, by definition, waste energy as they are inserted in series with the high current path. Current transformers do not suffer from this but can only measure AC signals, are bulky and prone to core saturation when tampered with, especially in smart meter applications.

Hall sensing addresses a number of these issues but, until now, has often required a slotted ferromagnetic core to ‘amplify’ the current signal for accurate measurement, adding bulk to the solution. The Melexis IMC-Hall® technology already partially addresses this with smaller shields.

Melexis’ new ‘plug and power’ integrated, IC-based, solution addresses all of these issues and offers a simple-to-use and intelligent current sensing solution for modern applications.

The Melexis MLX91210 is an Integrated Current Sensor that senses AC and DC current flowing through half of the leads of the SOIC package. The copper path exhibits very low power dissipation (0.7Ω – 0.8mΩ), compared to several milliohms for shunt solutions. As the current conductor position is fixed with respect to the monolithic CMOS sensor inside the plastic package, the fully integrated factory calibrated Hall-effect current sensor does not require any form of user calibration once mounted on the PCB.

Inside the package, the magnetic flux density is sensed differentially by two sets of Hall plates giving excellent stray-field immunity. The close proximity of the Hall plates to the current conductor overcomes the absence of a ferromagnetic concentrator and the factory calibration ensures an accurate signal over temperature. The small form factor of the surface mount sensors saves board space and cost, while maintaining basic isolation ratings as high as 2.5kVAC between the primary and secondary side package leads.

The device is ideally suited to sensing currents as high as 30ARMS in consumer and industrial applications such as power monitoring, server farms and motherboards, as well as motor control and load detection, power supplies and overcurrent detection.

Meeting the needs of modern power monitoring, the MLX91210 delivers a fully integrated and factory calibrated current sensor that provides fast and accurate results. It combines the sensing element, the signal conditioning and the voltage isolation in a standard surface mount package. Ideal for modern, compact applications the Plug and Power concept does not need any additional components such as a shunt resistor or ferromagnetic core.

FEATURES

  • For currents up to 30ARMS
  • From DC to 100kHz, 5μs response time
  • Miniature footprint
  • Factory calibrated analog output
  • Robust against external fields and cross-talk
  • Lowest electrical resistance down to 0.7mΩ
  • Voltage isolation up to 2.5kVRMS
  • Operating temperature -40 to +125°C

APPLICATIONS

  • Energy, consumer, industrial
  • Power monitoring and metering
  • Motor control, inverters, load detection
  • Overcurrent detection

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