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PDF A1120 Data sheet ( Hoja de datos )
| Número de pieza | A1120 | |
| Descripción | (A1120 - A1125) Chopper Stabilized Precision Hall Effect Switches | |
| Fabricantes | Allegro | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de A1120 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
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A1120, A1121, A1122, and A1125
Chopper Stabilized Precision Hall Effect Switches
Features and Benefits
▪ Unipolar switchpoints
▪ Resistant to physical stress
▪ Superior temperature stability
▪ Output short-circuit protection
▪ Operation from unregulated supply
▪ Reverse battery protection
▪ Solid-state reliability
▪ Small package sizes
Packages:
3-pin SOT23W (suffix LH)
Not to scale
3-pin SIP (suffix UA)
Description
The A1120, A1121, A1122, and A1125 Hall-effect, unipolar
switches are extremely temperature-stable and stress-resistant
sensor ICs, especially suited for operation over extended
temperature ranges to 150°C. Superior high-temperature
performance is made possible through dynamic offset
cancellation, which reduces the residual offset voltage normally
caused by device overmolding, temperature dependencies, and
thermal stress.
Each device includes on a single silicon chip a voltage regulator,
Hall-voltage generator, small-signal amplifier, chopper
stabilization, Schmitt trigger, and a short-circuit protected
open-drain output to sink up to 25 mA.
An on-board regulator permits operation with supply voltages
of 3 to 24 V. The advantage of operating down to 3 V is that
the device can be used in 3 V applications or with additional
external resistance in series with the supply pin for greater
protection against high voltage transient events.
For the A1120, A1121, and A1122, a south pole of sufficient
strength turns the output on. Removal of the magnetic field
turns the output off. The A1125 is complementary, in that for
thesehttp://www.DataSheet4U.net/ devices, a south pole turns the A1125 output off, and
removal of the magnetic field turns the output on.
Two package styles provide a magnetically optimized package
for most applications. Package type LH is a modified SOT23W,
surface mount package, while UAis a three-lead ultra-mini SIP
for through-hole mounting. Each package type is lead (Pb) free
(suffix, –T), with a 100% matte tin plated leadframe.
Functional Block Diagram
VCC
Amp
Regulator
Low-Pass
Filter
To All Subcircuits
Control
Current Limit
VOUT
A1120-DS, Rev. 12
GND
datasheet pdf - http://www.DataSheet4U.net/
1 page  
A1120, A1121, A1122
and A1125
Chopper Stabilized Precision Hall Effect Switches
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Package Thermal Resistance
Symbol
RθJA
Test Conditions
Package LH, 1-layer PCB with copper limited to solder pads
Package LH, 2-layer PCB with 0.463 in.2 of copper area each
side connected by thermal vias
Package UA, 1-layer PCB with copper limited to solder pads
Value Units
228 ºC/W
110 ºC/W
165 ºC/W
Power Derating Curve
TJ(max) = 165ºC; ICC = ICC(max)
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
Package LH, 2-layer PCB
(RQJA = 110 ºC/W)
10
9 Package UA, 1-layer PCB
(R = 165 ºC/W)8
7
QJA
Package LH, 1-layer PCB6
http://www.DataSheet4U.net/
5 (RQJA = 228 ºC/W)
4
3
2
VCC(max)
VCC(min)
20 40 60 80 100 120 140 160 180
Power Dissipation versus Ambient Temperature
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
20
(RPQaJAck=a(Rg1PQe6JaA5Uck=ºAaC1,g/11eW0-Ll)aºHCy,/eW2r-l)PayCeBr PCB
(RPQaJcAk=ag2e2L8HºC, 1/W-la)yer PCB
40 60 80 100 120 140 160 180
Temperature (°C)
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
datasheet pdf - http://www.DataSheet4U.net/
5 Page 
A1120, A1121, A1122
and A1125
Chopper Stabilized Precision Hall Effect Switches
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 ele-
ment. 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 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 magnetic
sourced signal then can pass through a low-pass filter, while the
modulated DC offset is suppressed. This configuration is illus-
trated in figure 2.
The chopper stabilization technique uses a 400 kHz high fre-
quency clock. For demodulation process, a sample and hold
technique is used, where the sampling is performed at twice the
chopper frequency (800 kHz). This high-frequency operation
allows a greater sampling rate, which results in higher accuracy
and faster signal-processing capability. This approach desensi-
tizes 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.
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 applications, Allegro
recommends its digital device families with lower sensitivity
to jitter.http://www.DataSheet4U.net/ For more information on those devices, contact your
Allegro sales representative.
Regulator
Hall Element
Clock/Logic
Amp
Low-Pass
Filter
Figure 2. Model of chopper stabilization technique
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
datasheet pdf - http://www.DataSheet4U.net/
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet A1120.PDF ] | |
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