A1126LLHLT-T Allegro Microsystems Inc, A1126LLHLT-T Datasheet - Page 10

• Manufacturer Part Number: A1126LLHLT-T
• Description: IC SW HALL EFFECT OMNI SOT23W
• Manufacturer: Allegro Microsystems Inc
• Series: -r
• Type: Omnipolar Switchr

Specifications of A1126LLHLT-T

• Sensing Range: ±55G Trip, ±50G Release
• Voltage - Supply: 3 V ~ 24 V
• Current - Supply: 4mA
• Current - Output (max): -
• Output Type: Digital, Open Drain
• Features: Ultra Sensitive
• Operating Temperature: -40°C ~ 150°C
• Package / Case: *
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 620-1421-2

A1126
Chopper Stabilization Technique
When using Hall-effect technology, a limiting factor for
switchpoint accuracy is the small signal voltage developed across
the Hall element. This voltage is disproportionally small relative
to the offset that can be produced at the output of the Hall sensor
chip. This makes it difficult to process the signal while main-
taining an accurate, reliable output over the specified operating
temperature and voltage ranges. Chopper stabilization is a unique
approach used to minimize Hall offset on the chip. The patented
Allegro technique, namely Dynamic Quadrature Offset Cancella-
tion, removes key sources of the output drift induced by thermal
and mechanical stresses. This offset reduction technique is based
on a signal modulation-demodulation process. The undesired
offset signal is separated from the magnetic field-induced signal
in the frequency domain, through modulation. The subsequent
demodulation acts as a modulation process for the offset, causing
the magnetic field-induced signal to recover its original spec-
Subject to Change Without Notice
Preliminary Datasheet
May 3, 2011
Hall Element
Figure 3. Concept of Chopper Stabilization Technique
V+
Chopper-Stabilized Omnipolar Hall-Effect Switch
Figure 2. Typical Application Circuit
C
0.1 μF
BYPASS
Regulator
Application Information
A1126
VCC
GND
trum at baseband, while the DC offset becomes a high-frequency
signal. The magnetic-sourced signal then can pass through a
low-pass filter, while the modulated DC offset is suppressed. The
chopper stabilization technique uses a 400 kHz high frequency
clock. For demodulation process, a sample-and-hold technique is
used, where the sampling is performed at twice the chopper fre-
quency. This high-frequency operation allows a greater sampling
rate, which results in higher accuracy and faster signal-processing
capability. This approach desensitizes the chip to the effects
of thermal and mechanical stresses, and produces devices that
have extremely stable quiescent Hall output voltages and precise
recoverability after temperature cycling. This technique is made
possible through the use of a BiCMOS process, which allows the
use of low-offset, low-noise amplifiers in combination with high-
density logic integration and sample-and-hold circuits.
VOUT
Clock/Logic
Amp
R
LOAD
Low-Pass
Filter
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
10