ACS704 Allegro Micro Systems, Inc., ACS704 Datasheet - Page 15

• Manufacturer Part Number: ACS704
• Manufacturer: Allegro Micro Systems, Inc.

Chopper Stabilization Technique
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 patented a Chopper Stabilization 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 modu-
lated 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 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.
ACS704ELC005-DS, Rev. 7
Concept of Chopper Stabilization Technique
Hall Element
ACS704ELC-005
Regulator
Clock/Logic
Amp
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
Low-Pass
Filter
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