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New AAL024 TDFN Current-Over-Trace Sensor from NVE

on Friday, 02 February 2018. Posted in News

New AAL024 TDFN Current-Over-Trace Sensor from NVE

The new AAL024-10E combines small size, high sensitivity, and cross-axis sensitivity for an ideal current-over-trace sensor.

AAL024 Over Trace

Key AAL024 features include:
  • Wheatstone bridge
    analog output
  • 3.6 mV/V/Oe typ. magnetic sensitivity
  • 1.5 – 10.5 Oe linear range
  • Up to 300 mV/A typ. current sensitivity (5V supply)
  • Omnipolar for AC or DC measurements
  • <4% nonlinearity
  • <2% hysteresis
  • 2.2 kΩ typ. bridge resistance
  • Operation to near-zero voltage
  • Ultraminiature 2.5 mm x 2.5 mm x 0.8 mm TDFN6

Download datasheet >

Evaluation Kit
AG903The AAL024 Evaluation Board includes four AAL024 sensors in four different circuit board configurations.
Board specifications include:
  • 2" x 2" (50 mm x 50 mm) PCB
    with four different
    current-trace configurations
  • Screw terminals for
    14 to 30 AWG wires
  • Current sensitivity to 60 mV/V/A typ. (300 mV/A with a 5V supply)
  • Up to 5 amp AC or DC noncontact current measurement

Reference Circuit:
Simple Bridge Sensor Amplifier
GMR sensors have high output signals without amplification, but if single-ended signals higher amplitude are needed, instrumentation amplifiers can minimize parts count:

20x Instrumentation Amplifier
AAL024 with an instrumentation amplifier.

The INA826 is an inexpensive instrumentation amplifier. The gain is limited to 20 to avoid saturating the amplifier.

The high-frequency cutoff frequency in this example is 1.5 kHz, set by the 0.1 µF capacitors and the 1.1 KΩ bridge output resistance (half the bridge resistance).

Since the instrumentation amplifier has a minimum output of 0.1 volts, to detect very low fields on a single supply, an offset can be provided by using a non-zero amplifier reference voltage. The reference voltage can also be used to trim out sensor offset voltage.

Current Sensing with an AAL024 Sensor
The new AAL024 analog magnetic sensor is designed for sensing current through a circuit-board trace. This type of current sensing is accurate, virtually lossless, provides inherent electrical isolation, and can be used for AC or DC.

This video demonstrates:

Current Sensor Demonstration Video
NVE’s current sensing Web application lets you simulate AAL024 sensor output with different current-carrying traces at various distances.

The handy app accommodates a variety of current-carrying traces and does the complex math for you:
Current sensing Web app

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