A1642LK-I1-T View Datasheet(PDF) - Allegro MicroSystems
Part Name
Description
MFG CO.
A1642LK-I1-T
Allegro MicroSystems
'A1642LK-I1-T' PDF : 13 Pages View PDF
A1642LK
Two-Wire True Zero-Speed Miniature Differential Peak-Detecting Sensor with Continuous Calibration
Functional Description
Sensing Technology
The single-chip differential Hall effect sensor IC possesses two
Hall elements, which sense the magnetic profile of the ring mag-
net simultaneously, but at different points (spaced at a 1.5 mm
pitch), generating a differential internal analog voltage, VPROC ,
that is processed for precise switching of the digital output
signal.
The Hall IC is self-calibrating and also possesses a temperature
compensated amplifier and offset compensation circuitry. Its
voltage regulator provides supply noise rejection throughout the
operating voltage range. Changes in temperature do not greatly
affect this device due to the stable amplifier design and the offset
compensation circuitry. The Hall transducers and signal process-
ing electronics are integrated on the same silicon substrate, using
a proprietary BiCMOS process.
Target Profiling
An operating device is capable of providing digital informa-
tion that is representative of the magnetic features on a rotating
target. The waveform diagram shown in figure 3 presents the
automatic translation of the magnetic profile to the digital output
signal of the sensor.
shown is: perpendicular to the leads, across the face of the
device, from the pin 1 side to the pin 4 side. This results in the
sensor output switching from high, ICC(High), to low ICC(Low),
as the leading edge of a north magnetic pole passes the sensor
face. In this configuration, the device output current switches to
its low polarity when a north pole is the target feature nearest to
the sensor. If the direction of rotation is reversed, then the output
polarity inverts.
Note that output voltage polarity is dependent on the position of
the sense resistor, RSENSE (see figure 4).
Target
Ring Magnet
Representative
Differential
Magnetic Profile
Sensor Electrical
Output Profile, IOUT
NS N S
Output Polarity
Figure 3 shows the output polarity for the orientation of target
and sensor shown in figure 2. The target direction of rotation
Figure 3. Output Profile of a ring magnet target for the polarity
indicated in figure 2.
VCC
VSUPPLY
Target
(Ring Magnet)
SN SN
Element Pitch
Hall Element 2
Hall Element 1
Hall IC
(Pin 4 Side)
(Pin 1 Side)
Figure 1. Relative motion of the target is detected by the dual Hall ele-
ments mounted on the Hall IC.
ICC
1
VCC
A1642
GND
4
VOUT(L)
RSENSE
RSENSE
VOUT(H)
1
VCC
A1642
GND
4
ICC
Rotating Target
Branded Face
of Sensor
14
Figure 2. This left-to-right (pin 1 to pin 4) direction of target rotation
results in a low output signal when a magnetic north pole of the target is
nearest the face of the sensor (see figure 3). A right-to-left (pin 4 to pin
1) rotation inverts the output signal polarity.
A1642LK-DS
I+
IOUT
V+
VOUT(L)
V+
VOUT(H)
Figure 4: Voltages profiles for high side and low side two-wire sensing.
Allegro MicroSystems, Inc.
8
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
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