Sensing the Hall effect
21 April 2009
Hall effect based current sensor family suitable for motor control applications.
High bandwidth, low power-loss current sensors from Allegro Microsystems have been launched by Solid State Supplies. The high current devices incorporate Allegro's proprietary amplifier and filter designs to enable noise performance down to 3 mV (typ) for 10 nF on VIOUT pin to GND. This Hall effect based current sensor family also features increased bandwidth of 120 kHz and low internal resistance of 100 µΩ, leading to low power loss.
Each device consists of a low-offset linear Hall effect sensor circuit with a copper conduction path located near 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 optimised through the close proximity of the conduction path to the Hall transducer. A proportional output voltage is provided by the low-offset, chopper-stabilised BiCMOS Hall IC.
The ACS758 family can be used for AC or DC current sensing in the range 50 A to 200 A, 3.0 V to 5.5 V. The thickness of the copper conductor allows survival of the device at up to 5x over-current conditions. The terminals of the conductive path are electrically isolated from the sensor leads, allowing the ACS758 family to be used in applications requiring electrical isolation without the use of opto-isolators or other isolation techniques.
Allegro's integrated shield technology reduces capacitive coupling from current conductor to die due to high dV/dt signals, and prevents offset drift in high side, high voltage applications. The ACS758 range is suited to applications including motor control, load detection and management, power supply and DC-DC converter control, inverter control and overcurrent fault detection.
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