Current sensor IC incorporates isolation

Paul Boughton
Allegro Microsystems Europe is launching the ACS710, a 120kHz bandwidth, high-voltage isolation current sensor IC that provides an economical and precise means of current sensing for applications in industrial, commercial and communications systems.
The new device consists of a precision linear Hall sensor integrated circuit with a copper conduction path located near the surface of the silicon die. Applied current flows through the copper conduction path and the analogue output voltage from the Hall sensor IC linearly tracks the magnetic field generated by the applied current. This patented packaging configuration gives excellent accuracy because the Hall element is situated very close to the current being measured.
In addition, the current conduction path is isolated electrically from the low-voltage sensor inputs and outputs. This allows the ACS710 family to be used in applications requiring electrical isolation without the use of opto-isolators or other costly isolation techniques.
Allegro's proprietary integrated shield technology leads to a high degree of immunity to voltage variations and stray electric fields in the current conductor, thereby ensuring low output ripple and low offset drift in high-side, high-voltage applications.
The voltage on the overcurrent input enables customers to define an overcurrent fault threshold for the device; when the current flowing through the copper conduction path exceeds this threshold, the open drain overcurrent fault pin switches to a logic 'low' state.
Allegro says that the internal resistance of the copper path used for current sensing is typically 1 milliohm, resulting in low power losses. The ACS710 can sense currents of 12.5-25A nominal and inrush peak currents three times higher than nominal, making it suitable for motor control applications. Other application areas include uninterruptible power supplies, power-supply protection, IGBT modules, energy metering and white goods controls.
Factory programming of the linear Hall sensor IC in the ACS710 results in exceptional accuracy in both analogue and digital output signals. The device is offered in a small footprint surface-mount package for easy implementation in customer applications.
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