ACS720: High Accuracy, Dual Fault, Galvanically Isolated Current Sensor in SOIC16 Widebody Package

The ACS720 is a 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 ACS720 is to provide high isolation with a reduced bill of materials made possible by the proprietary IC SOIC16W package. The ACS720 works off of a single 5 V supply while maintaining an output voltage swing from 0 to 3 V, with a stable zero current output of 1.5 V. This allows the ACS720 to operate off of a 5 V supply while having an output which is compatible with typical 3.3 V ADCs found on many MCUs. Furthermore, the ACS720’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 ACS720 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 ACS720 also integrates differential current sensing, which rejects external magnetic fields, greatly simplifying board layout in 3-phase motor applications.

Near closed-loop accuracy is achieved in this open-loop sensor due to Allegro’s 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.

The ACS720 is provided in a small surface-mount SOIC16 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. The device is fully calibrated prior to shipment from the factory.

• Differential current sensing cancels common mode fields, simplifying PCB layout
• Two user-settable faults for fast short-circuit protection and slower overcurrent detection
• Industry-leading noise performance with greatly improved bandwidth through proprietary amplifier and filter design techniques
• Patented integrated digital temperature compensation circuitry allows high accuracy over temperature in an open loop sensor
• 1.0 mΩ primary conductor resistance for low power loss and high inrush current-withstanding capability
• Small footprint, low-profile SOIC16 package suitable for space-constrained applications
• Integrated shield virtually eliminates capacitive coupling from current conductor to die due to high dV/dt voltage transients
• 5 V single supply operation with 0-3 V output swing
• Output voltage proportional to AC or DC current
• Factory-trimmed sensitivity and quiescent output voltage for improved accuracy
• 3600 Vrms Dielectric Strength certified under UL60950-1
• High PSRR for noisy environments