Fully Integrated, Hall Effect-Based Linear Current Sensor with

2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor

ACS713

10

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (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 asso-

ciated on-chip amplifier. Allegro patented 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 suppressed

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 tempera-

ture 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

Low-Pass

Filter

Concept of Chopper Stabilization Technique