AG003-01E NVE, AG003-01E Datasheet - Page 124

• 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

Application Notes
Offset Characteristics
When using the specified sensitivity to predict the output of a sensor, remember that the sensor
typically has a DC offset voltage. This is due to electrical bridge imbalance as well as external
magnetic field bias (earth’s field, magnets…). The output of the sensor without applying the current of
interest is the base line output. The effects of the current will be added to this base line value. For the
graphs shown on pages 130 and 131, the Y axis intercept is the base line offset. To determine the
output of the sensor for a given field, this Y intercept number must be added to the value obtained by
multiplying the current value by the slope.
AC
As mentioned previously, most information thus far has focused on DC applications. AC current
detection with an AA003-02 is unique and thus deserves special attention in a separate application.
Because the sensor is magnetically omni-polar, the output will be the same sign for either direction of
magnetic field. As an AC current changes direction, the field surrounding the conductor will also
change direction. The sensor’s output will produce a fully rectified output. Low current AC is
particularly laden with hysteretic errors. One method of creating both a bipolar output and a lower
error is to magnetically bias the sensor. Biasing is discussed above in this Engineering and Application
Notes booklet.
Part-to-Part Sensitivity
The data and evaluation thus far have focused on individual part performance. The part-to-part
performance will also be briefly examined here. Each current sensor is tested and sorted to be within
certain limits as given in the specification sections of this catalog. The main specification that affects
the output of the sensor is the sensitivity. The AA003-02 sensors are tested to a sensitivity range of 2.0
to 3.2 mV/V/Oe. The offset specification also affects the output. The offset is the zero current or
electrical imbalance of the Wheatstone bridge inside the sensor.
The magnetic field of the earth at NVE, is approximately 0.5G at a 70-degree angle to the horizon
(values will vary depending on geographical location). The effects of this magnetic field should be
analyzed in each application.
Care should be taken by the user to reduce the number and proximity of ferrous materials and magnetic
field producers around the sensor. This typically is not a concern, but in some highly populated boards,
this may be a necessity. Close proximity to such devices can increase the magnetic hysteresis or affect
the output. In turn, these devices will decrease the sensor’s output precision.
The output of the AA003-02 is functionally dependent on the distance between the sensor and the
current. The field from a current carrying conductor is inversely proportional to the distance from the
conductor. As the distance from the sensor to the conductor increases, the output from the sensor
decreases. Likewise, as the sensor moves closer to the conductor, the output will increase. For the data
analysis done in this report, the sensor was placed “live bug” over the current traces. In this
configuration, the actual sensor element is about 0.04" from the top of the PCB trace. The output will
increase with the current carrying conductor placed directly over-top of the sensor package. In this
configuration, the sensing element is approximately 0.02" from the surface of the conductor. This
distance change will account for an estimated doubling of sensor output.
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