ACS706 Family: Allegro Introduces New Bidirectional 1.5 milli-ohms Hall-Effect-Based Linear Current Sensor IC Family

Worcester, MA, Nov. 28, 2005 — Allegro MicroSystems, Inc. announces a new family of current sensor ICs that provide economical and precise solutions for current sensing in industrial, commercial, and communications systems. These are isolated integrated current sensing devices for easy implementation in customer applications. The ACS706 devices are bi-directional sensor ICs that can measure either AC or DC currents. The power lead frame is designed for extremely low power loss, and is electrically isolated from the sensor signal leads. This isolation allows ACS706 sensor ICs to be used in applications requiring electrical isolation without the addition of other isolation components. Typical applications include motor control, load detection and management, switched-mode power supplies, and overcurrent fault protection.

The ACS706 family consists of a precision, low-offset linear Hall sensor circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which is sensed by the integrated Hall IC and converted into a proportional voltage. Device accuracy is optimized through the close proximity of the magnetic signal to the Hall transducer. A precise, proportional voltage is provided by the low-offset, chopper-stabilized BiCMOS Hall IC, which is programmed for accuracy at the factory.

The output of the devices have a positive slope (>VCC / 2) when an increasing current flows through the primary copper conduction path (from pins 1 and 2, to pins 3 and 4), which is the path used for current sensing. The internal resistance of this conductive path is typically 1.5 mΩ, providing low power loss. The thickness of the copper conductor allows survival of the device at up to 3 times the overcurrent conditions. The terminals of the conductive path are electrically isolated from the sensor leads (pins 5 through 8).

The ACS706 family is provided in a small, surface mount SOIC8 package (shown above). The leadframe is plated with 100% matte tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the flip-chip uses high-temperature Pb-based solder balls, currently exempt from RoHS. These devices are fully calibrated prior to shipment from the factory.

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