Data Sheet

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

ACS712

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Chopper Stabilization is an innovative circuit technique that is

used to minimize the offset voltage of a Hall element and an

associated on-chip amplifier. Allegro has a Chopper Stabiliza-

tion technique that nearly eliminates Hall IC output drift induced

by temperature or package stress effects. This offset reduction

technique is based on a signal modulation-demodulation process.

Modulation is used to separate the undesired DC offset signal

from the magnetically induced signal in the frequency domain.

Then, using a low-pass filter, the modulated DC offset is sup-

pressed while the magnetically induced signal passes through

the filter. As a result of this chopper stabilization approach, the

output voltage from the Hall IC is desensitized to the effects

of temperature and mechanical stress. This technique produces

devices that have an extremely stable Electrical Offset Voltage,

are immune to thermal stress, and have precise recoverability

after temperature cycling.

This technique is made possible through the use of a BiCMOS

process that allows the use of low-offset and low-noise amplifiers

in combination with high-density logic integration and sample

and hold circuits.

Chopper Stabilization Technique

Amp

Regulator

Clock/Logic

Hall Element

Sample and

Hold

Low-Pass

Filter

Concept of Chopper Stabilization Technique