New high isolation current sensor IC has dual fault user settable over-current fault outputs

Allegro MicroSystems has introduced a new high accuracy Hall-effect-based current sensor IC with multiple programmable fault levels intended for industrial and consumer applications with a focus on motor control and power inverter stage applications. One of the key benefits of the company’s ACS720 is to provide high isolation with a reduced bill of materials made possible by the proprietary IC SOIC-16W package. The device works off a single 5V supply while maintaining an output voltage swing from 0V to 3V, with a stable zero current output of 1.5V. This allows the device to operate off a 5V supply while having an output which is compatible with typical 3.3V ADCs found on many MCUs. Furthermore, the device’s high PSRR rejects the noise often found on the supplies in the power section of the PCB or system, maintaining high accuracy in noisy environments. The device has dual fault functions that are user configurable. Fast and slow fault output allow for short-circuit and overcurrent fault detection. A user-created resistor divider from the power supply of the device is used to set the fault level. The fault outputs are open drain, allowing the user to pull them up to a compatible voltage for the MCU. The open-drain outputs also allow for implementing a simple logical OR of multiple sensor fault outputs. The device also integrates differential current sensing, which rejects external magnetic fields, greatly simplifying board layout in three-phase motor applications. Near closed-loop accuracy is achieved in this open-loop sensor IC due to their patented, digital temperature compensation, ultimately offering a smaller and more economical solution for many current sensing applications that traditionally rely on closed-loop core based sensors.