Automotive Grade, Hall-Effect Sensor Offers 2.1 kVrms Isolation
Allegro introduced two current sensorsfor AC and DC currents in automotive applications. The ACS714 and ACS715 devices are akin to the company's ACS712 and 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°C 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 mO typical, providing low power loss. The thickness of the copper conductor allows survival of the device at up to 5× overcurrent conditions, according to the company. 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).