Sensors For High-Side Current Sensing Applications


The distinctive current sensor ICs for high-side current sensing applications have their conductive path terminals electrically isolated from the sensors leads when compared to conventional sensors which use high-side differential amplifiers or other costly isolation techniques to attain the desired output.

In high-side current sensing technique, the current is sensed in the supply path of the power connection to the monitored load. The current generally flows in just one direction. Accordingly, any switching can be performed on the load-side of monitor. The advantage of such a circuit is that load is grounded and the load is not activated by accidental short at power connection allowing detecting high load current caused by short.

Allegro’s ACS722 and ACS723 are the two current sensors which exhibit features such as enhanced performance, reduced power consumption and a wide operating temperature range with near zero magnetic hysteresis in a surface mount package. According to the press release, “The small package is ideal for space constrained applications while also saving costs due to reduced board area, yet provides a 4800 VRMS isolation rating, the highest available from Allegro surface mount current sensor ICs.”


Highlighting the operation of the device based on the linear Hall sensor circuit with a copper conduction path located near the surface of the chip, the release adds, “On application of current through the conduction wire, a magnetic field is sensed by the IC which converts into the proportional voltage. Device accuracy is optimised through the close proximity of the magnetic field to the Hall transducer. A precise, proportional voltage is provided by the low-offset, chopper-stabilised BiCMOS Hall IC, which includes Allegro’s patented digital temperature compensation, resulting in extremely accurate performance over temperature. The output of the device has a positive slope when increasing current flows through the primary copper conduction path, which is the path used for current sensing.”

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These new sensor ICs from Allegro are an economical and precise solution for AC or DC current sensing in industrial, commercial and communication typical suited for applications that include motor control, solar inverters, home automation and monitoring as well as those applications requiring reinforced isolation ranges.

Key features of ACS722 and ACS723 as listed below:

  • Patented integrated digital temperature compensation circuitry allows for near closed loop accuracy over temperature in an open loop sensor
  • Industry-leading noise performance with greatly improved bandwidth through proprietary amplifier and filter design techniques
  • Pin-selectable band width: 80 kHz for high bandwidth applications or 20 kHz for low noise performance.
  • Packages:
    • ACS722LLC: Small footprint, low-profile SOIC8 package suitable for space-constrained applications
    • ACS722KMA: Low-profile SOIC16 wide-body package suitable for space-constrained, high isolation applications
  • ACS722LLC: Integrated shield virtually eliminates capacitive coupling from current conductor to die, greatly suppressing output noise due to high dv/dt transients
  • 3 to 3.6 V, single supply operation output voltage proportional to AC or DC current
  • Factory-trimmed sensitivity and quiescent output voltage for improved accuracy
  • Chopper stabilisation results in extremely stable quiescent output voltage
  • Nearly zero magnetic hysteresis
  • Ratiometric output from supply voltage


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