CFS1000 Programmable SMD-packaged AMR current sensor

The CFS1000 is designed for the magnetic measurement of DC, AC or pulsed currents. The compact, coreless current sensor offers a high design flexibility with its wide measuring range. Its closed-loop-principle offers a high linearity. The differential field measurement principle, offers a high interference field suppression.

  • Galvanic isolation
  • Coreless current measurement up to 1000 A
  • Compensated differential field measurement (closed-loop-principle)
  • High bandwidth current measurement: DC, AC (up to 500 kHz)
  • Fast overcurrent detection with tunable threshold
  • AEC-Q100 qualified

The measurement range of the current sensor is defined by the current path geometry of an external busbar, which can be implemented directly into the printed circuit board for small currents. As a result, the sensor can be used extremely flexibly for small as well as for large currents.

We provide simple design tools as well as design support by our experts to realize the perfect busbar layout for your measurement range.

  • Primary current IPN up to 1000 A
  • Measurement range up to three times IPN (Peak)
  • High linearity
  • Low temperature dependency
  • No hysteresis and saturation effects
  • Excellent accuracy
  • Temperature range -40 °C to +125 °C
  • Large signal-to-noise ratio
  • Standard SMD SO16w package

    The CFS1000 in SMD housing and unipolar 5 V supply voltage is suitable, for example, for measurement tasks in the areas:

    • Electrical speed drives (industry, e-mobility)
    • Power electronic inverters and converters
    • Photovoltaics (micro inverters)
    • Switching power supplies
    • Uninterruptible power supply

    General information

    The programmable CFS1000 current sensor is designed for highly dynamic, magnetic measurements of DC, AC or pulsed currents. The CFS1000 is a closed-loop current transformer consisting of an AMR sensor chip, two bias magnets and a signal conditioning ASIC that are all packaged in a standard SMD SO16w package.

    Contactless and in particular high bandwidth current measurements up to 500 kHz in the range of 10 A to 1000 A are possible. The measuring range of the current sensor is defined by the geometry of an external busbar. Due to the differential field measurement principle, the CFS1000 also offers a high interference field suppression.

    The high sensitivity of the used Anisotropic MagnetoResistive (AMR) effect enables excellent dynamic response without hysteresis or saturation effects, as present in current measurement systems using iron-cores. The large measuring range allows the customer a high degree of design flexibility, since a wide variety of measuring tasks can be handled with just one sensor type.

    The CFS1000 is a compact, low-cost yet high-quality current sensor with automotive qualification according to AEC-Q100. The concept as a pre-qualified measuring cell enables fast adaptation, with low engineering effort, to customer-specific applications in modern power electronics.

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    Technical data

    SymbolParameterMin.Typ.Max.Unit
    VDDSupply voltage4.755.05.25V
    IPNPrimary nominal current (RMS) 1)10-1000A
    IoutOutput current at IPN-2-mA
    fCOUpper cut-off frequency (-3 dB) -500-kHz
    εΣOverall accuracy (T = 25 °C; calibrated) 2)--±1%
    TεΣOverall accuracy (T = -40 to +125 °C; calibrated) 2)--±2%
    TambAmbient temperature-40-+15°C

    1) Primary nominal current range is defined by the geometry of the external primary current bar. As measuring range threefold absolute nominal current is guaranteed, restricted to 1 s in a 60 s interval.

    2) Overall accuracy error includes offset, linarity and sensitivity error (εΣ = εG + εoff + εlin).

    Measurement principle

    The primary current to be measured is fed below the sensor usually through a U-shaped current conductor, as for example a busbar. In this way, a magnetic differential field (gradient) is generated between both sides of the conductor, which is measured by the sensor element. By measuring the field gradient at two measurement points being in close proximity, an excellent stray field immunity is achieved. The modulation of the sensor element is compensated by a magnetic counter field on the AMR-sensor chip. The value for this required compensating current is the proportional measure for the primary current and represents the output signal of the sensor. Based on the compensation of the primary field (closed-loop-principle), a high linearity is realized.

    Busbar design

    The busbar is specially adapted for your application. The geometry of the busbar is crucial for the optimal performance of the CFS1000. For the first analytical estimation of the busbar geometry as well as the resulting sensor performance you can use our free simulation tool "Calc-U-Bar".

    In addition, we offer the option of having your busbar optimally designed by our experts for your application – using a 3D FEM simulation. Here, the influence of frequency effects or interferences coming from adjacent conductors towards the CFS1000 can be investigated.

    High flexibility: For currents of 100 A or more, the conductor can be routed as a solid busbar on the back of a printed circuit board, whereas for smaller currents, the conductor track is routed inside the circuit board underneath the sensor.

    Evaluation Board

    Evaluation boards are available for the CFS1000 current sensor.

    For this board, the primary current can be fed in easily via large contact points. All sensor signals can be easily reached using screw terminals or measurement terminals.

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      Application information about the CFK1000 evaluation boards

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