High Bandwidth, Fast Fault Response Current Sensor IC In Thermally Enhanced Package


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The Allegro ACS709 current sensor IC provides economical and precise means for current sensing applications in industrial, automotive, commercial, and communications systems. The device is offered in a small footprint surface mount package that allows easy implementation in customer applications.

The ACS709 consists of a precision linear Hall sensor integrated circuit with a copper conduction path located near the surface of the silicon die. Applied current flows through the copper conduction path, and the analog output voltage from the Hall sensor IC linearly tracks the magnetic field generated by the applied current. The accuracy of the ACS709 is maximized with this patented packaging configuration because the Hall element is situated in extremely close proximity to the current to be measured.

High level immunity to current conductor dV/dt and stray electric fields, offered by Allegro proprietary integrated shield technology, guarantees low output ripple and low offset drift in high-side applications.

The voltage on the Overcurrent Input (VOC pin) allows customers to define an overcurrent fault threshold for the device. When the current flowing through the copper conduction path (between the IP+ and IP– pins) exceeds this threshold, the open drain Overcurrent Fault pin will transition to a logic low state. Factory programming of the linear Hall sensor IC inside of the ACS709 results in exceptional accuracy in both analog and digital output signals.

The internal resistance of the copper path used for current sensing is typically 1.1 mΩ, for low power loss. Also, the current conduction path is electrically isolated from the low voltage device inputs and outputs. This allows the ACS709 family of sensor ICs to be used in applications requiring electrical isolation, without the use of opto-isolators or other costly isolation techniques.

  • Industry-leading noise performance with 120 kHz bandwidth through proprietary amplifier and filter design techniques
  • Integrated shield greatly reduces capacitive coupling from current conductor to die due to high dV/dt, and prevents offset drift in high-side applications
  • Small footprint surface mount QSOP24 package
  • 2100 VRMS isolation voltage between primary current path and sensor IC electronics
  • 1.1 mΩ primary conductor resistance for low power loss
  • User-settable Overcurrent Fault level
  • Overcurrent Fault signal typically responds to an overcurrent condition in <2 µs
  • Filter pin capacitor sets analog signal bandwidth
  • ±2% typical output error
  • 3 to 5.5 V, single supply operation
  • Factory trimmed sensitivity, quiescent output voltage, and associated temperature coefficients
  • Chopper stabilization results in extremely stable quiescent output voltage
  • Ratiometric output from supply voltage

This device is supplied in a 24-pin QSOP (suffix LF) package.

LF Package Documentation

Part Number Specifications and Availability

Documentation and Resources


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All Types Certificate
Documents Found: 32
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Certificate of Compliance 20110708 E333868
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Documents Found: 32
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Gerber File
ASEK709 Gerber Files
Hardware Kit or Board
ASEK709 Demo Board Tutorial
Simulation Tool
Current Sensor Error and Resolution
ACS LTspice Library