A3422LKA Allegro Microsystems Inc, A3422LKA Datasheet - Page 7

• Manufacturer Part Number: A3422LKA
• Description: IC SENSOR DIRECT/DETECT 5-SIP
• Manufacturer: Allegro Microsystems Inc
• Type: Special Purposer

Specifications of A3422LKA

• Sensing Range: 75G Trip, -75G Release
• Voltage - Supply: 4.5 V ~ 18 V
• Current - Supply: 18mA
• Current - Output (max): 30mA
• Output Type: Digital, Open Collector
• Features: High Sensitivity
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 5-SIP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

6
3422
HALL-EFFECT,
DIRECTION-DETECTION
SENSOR IC
The integrated circuit contains an internal voltage regula-
tor that powers the Hall elements 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 CMOS logic
circuitry that decodes the direction of rotation of the ring
magnet.
Quadrature/Direction Detection. Internal logic
circuitry provides outputs representing speed and direction
of the magnetic field across the face of the package. For
the direction signal to be appropriately updated, a quadra-
ture relationship must be maintained between the ring
magnet pole width*, the element-to-element spacing, and,
design, the device should be actuated with a ring magnet
pole width* two times the sensor-to-sensor 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 that has a period that satisfies the rela-
tionship n Τ /4 = 1.5 mm, where n is any odd integer.
Therefore, ring magnets with pole-pair spacings equal to 6
mm (n = 1), 2 mm (n = 3), 1.2 mm (n = 5), etc. are permit-
ted.
produced by a rotating ring magnet is shown on page 2.
Note the phase shift between the two elements.
stated as “pole pair” (North and South).
to a lesser extent, the magnetic switch points. For optimal
The response of the device to the magnetic field
*“Pole” refers to a single pole (North or South) unless
Functional Description
Worcester, Massachusetts 01615-0036 [phone]
, Box 15036
Outputs. The device provides three saturated outputs:
DIRECTION, E1 OUTPUT, and SPEED. DIRECTION
provides the direction output of the device and is defined
as OFF (high) for the direction E1 to E2 and ON (low) for
the direction E2 to E1. SPEED provides an XOR’d output
of the two elements. Because of internal delays, DIREC-
TION will always be updated before SPEED and is
updated at every transition of E1 OUTPUT and E2 OUT-
PUT (internal) allowing the use of up-down counters
without the loss of pulses.
Power-On State. At power on, the logic circutry is reset
to provide an OFF (high) at DIRECTION and an OFF
(high) for E1 and E2 (internal) for magnetic fields less
than B
powered up and either element detects a field between B
and B
B
OP
, the internal logic will set accordingly.
RP
OP
. If either element is subjected to a field greater than
. This eliminates ambiguity when the device is
O P