A1171EEWLT-P Allegro Microsystems Inc, A1171EEWLT-P Datasheet - Page 8

• Manufacturer Part Number: A1171EEWLT-P
• Description: IC HALL EFFECT SWITCH 6-DFN/MLP
• Manufacturer: Allegro Microsystems Inc
• Type: Omnipolar, Unipolar Switchr

Specifications of A1171EEWLT-P

• Sensing Range: ±55G Trip, ±6G Release
• Voltage - Supply: 1.65 V ~ 3.5 V
• Current - Supply: 2mA
• Current - Output (max): ±1mA
• Output Type: Digital, Push-Pull
• Features: High Sensitivity
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 6-XFDFN Exposed Pad
• Operate Point Typ: 30G
• Termination Type: SMD
• No. Of Pins: 6
• Hall Effect Type: Switch
• Supply Voltage Min: 1.65V
• Operating Temperature Max: 85°C
• Peak Reflow Compatible (260 C): Yes
• Supply Voltage: 3.5V
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Leaded Process Compatible: Yes
• Operating Temperature Min: -40°C
• Output Current: 1mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 620-1232-2

A1171
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 element. This makes it difficult to process the signal while
maintaining an accurate, reliable output over the specified oper-
ating 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 Cancellation, 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 spectrum at baseband,
while the dc offset becomes a high-frequency signal. The mag-
netic sourced signal then can pass through a low-pass filter,
Figure 4. Chopper Stabilization Circuit (Dynamic Quadrature Offset Cancellation)
Hall Element
Micropower Ultrasensitive Hall Effect Switch
Regulator
while the modulated dc offset is suppressed. This configuration
is illustrated in figure 4.
The chopper stabilization technique uses a high frequency clock.
For demodulation process, a sample and hold technique is used,
where the sampling is performed at twice the chopper frequency.
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.
The repeatability of magnetic field-induced switching is affected
slightly by a chopper technique. However, the Allegro high
frequency chopping approach minimizes the affect of jitter and
makes it imperceptible in most applications. Applications that
are more likely to be sensitive to such degradation are those
requiring precise sensing of alternating magnetic fields; for
example, speed sensing of ring-magnet targets. For such applica-
tions, Allegro recommends its digital device families with lower
sensitivity to jitter. For more information on those devices,
contact your Allegro sales representative.
Clock/Logic
Amp
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
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