A3423LK-T Allegro Microsystems Inc, A3423LK-T Datasheet - Page 6

• Manufacturer Part Number: A3423LK-T
• Description: IC DIRECTION SENSOR 2CH 4-SIP
• Manufacturer: Allegro Microsystems Inc
• Type: Special Purposer

Specifications of A3423LK-T

• Package / Case: 4-SIP
• Sensing Range: 55G Trip, -55G Release
• Voltage - Supply: 3.8 V ~ 24 V
• Current - Supply: 14mA
• Current - Output (max): 30mA
• Output Type: Digital, Open Collector
• Features: Regulated Voltage
• Operating Temperature: -40°C ~ 150°C
• Output Current: 30mA
• Sensor Case Style: SIP
• No. Of Pins: 4
• Supply Voltage Range: 3.8V To 24V
• Operating Temperature Range: -40°C To +150°C
• Base Number: 3423
• Supply Voltage: RoHS Compliant
• Svhc: No SVHC (15-Dec-2010)
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 620-1207

A3423
The integrated circuit contains an internal voltage regulator that
powers the Hall sensors and both the analog and digital circuitry.
This regulator allows operation over a wide supply voltage range
and provides some immunity to supply noise. The device also
contains logic circuitry that decodes the direction of rotation of
the ring magnet.
Quadrature/Direction Detection
outputs representing the speed and direction of the magnetic
field across the face of the package. For the direction signal to be
appropriately updated, a quadrature relationship must be main-
tained between the target magnetic pole width, the pitch between
the two Hall elements (E1 and E2) in the sensor, and, to a lesser
extent, the magnetic switchpoints.
For optimal design, the sensor should be actuated by a ring
magnet that presents to the front of the sensor a field with a pole
width two times the Hall element-to-element spacing. This will
produce a sinusoidal magnetic field whose period (denoted as Τ)
is then four times the element-to-element spacing. A quadrature
relationship can also be maintained for a ring magnet with fields
having a period that satisfies the relationship:
where n is any odd integer. Therefore, ring magnets with pole-
pair spacing equal to 6.52 mm (n = 1), 2.17 mm (n = 3), 1.3 mm
(n = 5), and so forth, are permitted.
(OUTA XOR
OUTB
OUTA
OUTB)
SPD
DIR
+B
–B
+B
–B
0
0
Target changes direction of rotation
nΤ/4 = 1.63 mm ,
Figure 1
Dual Channel Hall Effect Direction Detection Sensor
Internal logic circuitry provides
t
d
Functional Description
The response of the device to the magnetic field produced by a
rotating ring magnet is shown in the Performance Characteristics
section. Note the phase shift between the two integrated Hall ele-
ments.
Outputs
direction (DIR pin), E1 sensor output (OUTA pin), E2 sensor
output (OUTB pin), and target speed (SPD pin).
DIR provides the direction output of the sensor and is defined as
off (high) for targets moving in the direction from E1 to E2 and
on (low) for the direction E2 to E1. SPD provides an XORed
output of the two Hall elements (see figure 1). Because of inter-
nal delays, DIR is always updated before SPD and is updated at
every transition of OUTA and OUTB (internal) allowing the use
of up-down counters without the loss of pulses.
Power-on State
vide an off (high) state for all the outputs. If any of the channels
is subjected to a field greater than B
accordingly, and the outputs will switch to the expected state.
Power-on Time
when the supply voltage reaches the device supply minimum
until the device output becomes valid (see figure 2).
The device provides up to four saturated outputs: target
This characteristic, t
At power on, the logic circuitry is reset to pro-
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
Figure 2
OP
ON
, the internal logic will set
, is the elapsed time from
6