Automotive Electronics

Allegro Announces Automotive Grade, Hall-Effect Based Linear Current Sensors

Allegro Microsystems announced two new current sensors engineered to provide economical and precise sensing solutions for ac and dc currents in automotive applications. The ACS714 and ACS715 devices are designed and tested to meet the stringent requirements of automotive applications.

These devices are akin to the ACS712 & ACS713 devices, which are specialized for low current sensing in non-automotive applications. The differences are realized in the more rigorous test regiment over the full automotive temperature range (-40 to +150 °C) and the greater detail in the specification for error components. The latter will allow customers to determine the total error for the given system based.

The devices consist of a precise, 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 after packaging.

The internal resistance of this conductive path is 1.2 mΩ typical, providing low power loss. The thickness of the copper conductor allows survival of the device at up to 5x overcurrent conditions. The terminals of the conductive path are electrically isolated from the sensor leads (pins 5 through 8). This allows the ACS714 and ACS715 current sensors to be used in applications requiring electrical isolation without the use of opto-isolators or other costly isolation techniques.

The conductive shield across the face of the ACS714/15 is connected to ground, so that in the presence of high dV/dt events on the device conductor, it will shunt the resulting capacitively coupled energy. This prevents output voltage disturbances in the presence of very high conductor dV/dt events (which are often present in motor control and switched-mode power supply applications).

Both devices are provided in a small, surface mount SOIC8 package. The leadframe is plated with 100% matte tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the device is Pb-free, except for flip-chip high-temperature Pb-based solder balls, currently exempt from RoHS.

Allegro’s ACS714/15 are priced at $1.39 and $1.46 for the extended ("E") and automotive ("L") temperature ranges, respectively, in quantities of 1,000 units and have a 14-week typical lead-time.

Allegro MicroSystems Inc.
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