AG003-01E NVE, AG003-01E Datasheet - Page 94

• Manufacturer Part Number: AG003-01E
• Description: ASSEMBLY CURRENT SENSOR EVAL
• Manufacturer: NVE

Specifications of AG003-01E

• Sensor Type: Magnetic. GMR (Giant Magnetoresistive)
• Interface: Analog
• Embedded: No
• Utilized Ic / Part: AA Series Current Sensors
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Sensitivity: -
• Sensing Range: -
• Other names: 391-1060

GMR Magnetic Field Sensors (Magnetometers)
The NVE standard line of magnetic field sensors use a unique configuration employing a Wheatstone
bridge of resistors and various forms of flux shields and concentrators. Using magnetic materials for
shielding eliminates the need for a bias field with GMR sensors. NVE has developed a process to
plates a thick layer of magnetic material on the sensor substrate. This layer forms a shield over the
GMR resistors underneath, essentially conducting any applied magnetic field away from the shielded
resistors. The configuration allows two resistors (opposite legs of the bridge) to be exposed to the
magnetic field. The other two resistors are located under the plated magnetic material, effectively
shielding them from the external applied magnetic field. When the external field is applied, the
exposed resistors decrease in electrical resistance while the other resistor pair remain unchanged,
causing a signal output at the bridge terminals.
The plating process developed by NVE for use in GMR sensor applications has another benefit: it
allows flux concentrators to be deposited on the substrate. These flux concentrators increase the
sensitivity of the raw GMR material by a factor of 2 to 100. The flux concentration factor is roughly
equivalent to the length of one shield divided by the length of the gap. This allows use of GMR
materials that saturate at higher fields. For example, to sense a field from 0 to 100 Oersteds, NVE
deposits a GMR sensor that saturates at a nominal 300 Oersteds and flux concentrators with a
magnification factor of three. The figure below shows the basic layout of the device:
Bonding pads (4)
(100µm x 100µm)
Silicon substrate
(1300 µm x 400 µm)
T
YPICAL
www.nve.com
GMR M
Gap
phone: [phone] fax: [phone]
AGNETIC
Magnetically active resistor pair
Axis of sensitivity
- 94 -
Flux concentrator (2)
F
IELD
S
ENSOR
Magnetically shielded resistor (2)
Application Notes
L
AYOUT
Metal interconnects