Introduction of MEMSIC Magnetic Sensor Solution

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Introduction of MEMSIC Magnetic Sensor Solution
2
Agenda

• Background Knowledge
• MEMSIC Magnetic Sensor Solution
• Advantage of MEMSIC Magnetic Sensor Application
  Solution (Cellphone)

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Background Knowledge
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The Magnetic Effect

• Magnetic, a basic physical effect
• Magnetic field can be generated by magnet or
  electrical circuit.
• Magnetic field directs from Magnetic North to
  South.
• Like magnet repel each other, unlike magnet
  attract.

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Earths Geomagnetic Field

• General Earths Surface H 48 A/m (0.6 Oe) B
  0.6 x 10-4 Tesla (0.6 Gauss)

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Geomagnetic Field Compass for Orientation

• Geomagnetic field behaves like there is a big
  magnet inside the earth.
• Geomagnetic north pole is near earths South
  pole, geomagnetic south pole is near earths
  north pole.
• Compass is a small piece of magnet, attracted by
  geomagnetic field. Mag north heads earths north,
  mag south heads south.

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How to feel/detect Geomagnetic Field

• Traditional mechanical Compass related tools
• Electronics devices, MEMS Sensor technology

New MEMS sensor technology
Traditional mechanical tools
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Geomagnetic Inclination Orientation Projection

• Geomagnetic field is not constant all around the
  world, and normally neither vertical nor
  horizontal.
• Northern Hemisphere the field points DOWN,
  Southern Hemisphere the field points UP, quarter
  is almost vertical.
• A 3D Mag sensor is measuring the 3D vector
  geomagnetic filed, need be projected to a 2D
  vector in the ground plane to indicate the
  orientation.

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MEMSIC Magnetic sensor Technology
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MEMSIC Magnetic Sensor - AMR

• In non-working stage, the ARM elements in MEMSIC
  mag sensor only have random magnetization
  direction, so no overall magnetized
  characterization shown (Soft magnet).
• When AMR sensor need to perform measuring, apply
  magnetization to polarize magnetic field
  directionality in AMR element to establish normal
  measurement status.
• Due to the soft induced directional magnetization
  will gradually lose directionality, magnetization
  operation will be performed timely to maintain
  the measurement status.

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MEMSIC Magnetic Sensor

• Based on Anisotropic Magneto-Resistive (AMR)
  technology
• Fully integrated sensors with minimal external
  components
• Measures full range of 4 gausses
• Linear biasing
• Small, low-profile packaging
• Power up/down function available through I2C
  interface
• 13 bit ADC, 512 counts/gauss resolution
  (2mGauss/LSB)
• I2C Slave, FAST (400 KHz) mode
• Low Power Consumption
• MMC314x Tri-axis Magnetic Sensor Typically
  0.55mA_at_3V with 50 measurements per second

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MEMSIC Magnetic Sensor

• MMC314x
• Tri-Axis Magnetic Sensor
• I2C Interface
• /- 4Gauss Measurement Range
• 3x3x1 mm package
• MMC214x
• Dual-Axis Magnetic Sensor
• I2C Interface
• /- 4Gauss Measurement Range
• 3x3x0.7 mm package

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MEMSIC Magnetic Sensor

• Current only applies when taking measurement,
  thus lower current consumption.
  (0.01mA/Measurement)
• Magnetization coil to re-direct magnetization to
  maintain directionality over time, as well as
  good zero-point offset.
• High accuracy due to Wheatstone bridge resistance
  change. (512DAC/Gauss, 2mGauss Resolution)
• High sensitivity even across temperature change.
• The reaction of the magneto resistive effect is
  very fast (7mS/Measurement)

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AMR Anisotropic Magneto Resistive

• Resistivity changes as a function of the angle
  between the current generated magnetized field
  direction and the external magnetic field.
• Apply current ONLY when you need to measure
  external magnetic field.

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Measurement Range of Magnetic Sensor Technology