ACS726: Galvanically Isolated Current Sensor IC With Differential Output and Externally Adjustable Gain


The Allegro ACS726 current sensor IC family provides economical and precise solutions for AC current sensing in industrial, commercial, and communications systems. The device package allows for easy implementation by the customer. Typical applications include motor control, load detection and management, switched-mode power supplies, and overcurrent fault protection.

The fully differential output gives superior immunity to output offset drift as well common mode noise.

ACS726 is the first current sensor IC to include a fully differential back-end amplifier (BEA) that can be used to adjust gain and bandwidth via external RC networks. The BEA is fully independent and when unused, it can be powered down to reduce power consumption.

The device consists 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 field 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 output of the device has a positive differential voltage (VOUTP – VOUTN) when an increasing current flows through the primary copper conduction path (from pins 1 through 6, to pins 7 through 12), which is the path used for current sensing. The internal resistance of this conductive path is 1.1 mΩ typical, providing low power loss.

The terminals of the conductive path are electrically isolated from the sensor IC signal leads (pins 13 through 24). This allows the ACS726 current sensor IC to be used in high-side current sense applications without the use of high-side differential amplifiers or other costly isolation techniques.

The ACS726 is provided in a small, low-profile surface mount QSOP24 package (suffix LF). 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, excluding the BEA, is fully calibrated prior to shipment from the factory.

Top Features

  • Fully differential architecture for improved immunity to offset drift and common mode noise
  • Spare differential back end amplifier for externally adjustable gain and bandwidth using simple RC networks
  • Greatly improved bandwidth through proprietary amplifier and filter design techniques
  • High bandwidth 120 kHz analog output
  • Patented integrated digital temperature compensation circuitry allows nearly closed-loop accuracy, through entire temperature range, in an open loop sensor
  • 1.1 mΩ primary conductor resistance for low power loss and high inrush current withstanding capability
  • Small footprint, low-profile QSOP24 package suitable for space-constrained applications
  • Integrated shield virtually eliminates capacitive coupling from current conductor to die due to high dV/dt voltage transients
  • 3 to 3.6 V, single supply operation
  • Factory-trimmed sensitivity and quiescent output voltage for improved accuracy
  • Chopper stabilization results in extremely stable quiescent output voltage
  • Ratiometric output from supply voltage

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
ASEK726LLF-20B-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Distributor Stock
ASEK726LLF-40B-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Distributor Stock
ACS726LLFTR-20B-T 24-lead QSOP -40°C to 150°C Yes View Data Contact your
local sales rep
Distributor Stock
ACS726LLFTR-40B-T 24-lead QSOP -40°C to 150°C Yes View Data Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.

Design Support Tools

Allegro MicroSystems, LLC provides Gerber files for reference only. Any material, information, or instructions are provided AS IS without warranty of any kind. It is the responsibility of the User(s) to optimize any Printed Circuit Board (PCB) layout, as well as the selection of any components, for the specific application of the User(s).