A1645LK-I2 Allegro Microsystems Inc, A1645LK-I2 Datasheet - Page 8

• Manufacturer Part Number: A1645LK-I2
• Description: IC SENSOR HALL EFFECT AC 4-SIP
• Manufacturer: Allegro Microsystems Inc
• Type: Special Purposer

Specifications of A1645LK-I2

• Sensing Range: 120mV Trip, 120mV Release
• Voltage - Supply: 4 V ~ 24 V
• Current - Supply: 8.4mA
• Output Type: Digital, Open Collector
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 4-SIP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Output (max): -
• Features: -

A1642
Figure 1. Relative motion of the target is detected by the dual Hall ele-
ments mounted on the Hall IC.
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 device (see fi gure 3). A right-to-left (pin 4 to pin
1) rotation inverts the output signal polarity.
Sensing Technology
The single-chip differential Hall effect sensor IC possesses two
Hall elements, which sense the magnetic profi le of the ring mag-
net simultaneously, but at different points (spaced at a 1.5 mm
pitch), generating a differential internal analog voltage, V
that is processed for precise switching of the digital output
signal.
The Hall IC is self-calibrating and also possesses a temperature
compensated amplifi er 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 amplifi er 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 fi gure 3 presents the
automatic translation of the magnetic profi le to the digital output
signal of the device.
Output Polarity
Figure 3 shows the output polarity for the orientation of target
and device shown in fi gure 2. The target direction of rota-
(Ring Magnet)
Rotating Target
Hall Element 2
Target
(Pin 4 Side)
S
N
Peak-Detecting Sensor IC with Continuous Calibration
S
1
4
N
Two-Wire True Zero-Speed Miniature Differential
(Pin 1 Side)
Element Pitch
Hall Element 1
Hall IC
Functional Description
Branded Face
of Device
PROC
,
tion 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
device output switching from high, I
as the leading edge of a north magnetic pole passes the device
face. In this confi guration, the device output current switches to
its low polarity when a north pole is the target feature nearest to
the device. 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, R
Figure 4: Voltage profi les for high side and low side two-wire sensing.
Figure 3. Output Profi le of a ring magnet target for the polarity
indicated in fi gure 2.
Target
Ring Magnet
Representative
Differential
Magnetic Profile
Device Electrical
Output Profile, I
I
V
V
OUT
OUT(L)
OUT(H)
I+
V+
V+
OUT
SENSE
A1642
GND
VCC
4
1
V
CC
(see fi gure 4).
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
V
R
I
OUT(L)
CC
SENSE
N
S
CC(High)
A1642
V
N
GND
SUPPLY
VCC
4
1
, to low I
R
V
I
CC
OUT(H)
SENSE
S
CC(Low)
,
8