A3064: AC Coupled Hall-Effect Gear-Tooth Sensor IC

A3064
Hall Effect Gear Tooth Sensor IC, AC Coupled
Discontinued Product
These parts are no longer in production The device should not be
purchased for new design applications. Samples are no longer available.
Date of status change: October 31, 2005
Recommended Substitutions:
For new customers and applications, refer to the A1421LK.
NOTE: For detailed information on purchasing options, contact your
local Allegro field applications engineer or sales representative.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a
product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The information
included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor
for any infringements of patents or other rights of third parties which may result from its use.
Data Sheet
27612.21B
3064
HALL-EFFECT GEAR-TOOTH SENSOR IC
—AC COUPLED
X
The A3064LKA ac-coupled Hall-effect gear-tooth sensor IC is a
monolithic integrated circuit that switches in response to changing
differential magnetic fields created by moving ferrous targets. This
device is ideal for use in non-zero-speed, gear-tooth-based speed,
position, and timing applications such as in anti-lock braking systems,
transmissions, and crankshafts.
X
2
3
4
OUTPUT
GROUND
FILTER
5
FILTER
1
SUPPLY
VCC
Dwg. PH-011-1
Pinning is shown viewed from branded side.
ABSOLUTE MAXIMUM RATINGS
at TA = +25°C
Supply Voltage, VCC ............................. 24 V
When coupled with a back-biasing magnet, the device can be
configured to turn on or off with the leading or trailing edge of a geartooth or slot. Changes in fields on the magnet face caused by a moving
ferrous mass affect the two Hall transducers and are
differentially amplified by on-chip electronics. This differential
design provides immunity to radial vibration within the
device’s operating air gap. Steady-state magnet and system offsets are
eliminated using an on-chip differential band-pass filter. This filter
also provides relative immunity to interference from RF and electromagnetic sources. The on-chip temperature compensation and Schmitt
trigger circuitry minimizes shifts in effective working air gaps and
switch points over temperature, allowing operation to low frequencies
over a wide range of air gaps and temperatures.
Each Hall-effect digital Integrated circuit includes a voltage
regulator, two quadratic Hall-effect elements, temperature
compensating circuitry, a low-level amplifier, band-pass filter, Schmitt
trigger, and an open-collector output driver. The on-board regulator
permits operation with supply voltages of 4.5 to 24 volts. The output
stage can easily switch 20 mA over the full frequency response range
of the device and is compatible with bipolar and MOS logic circuits.
The device is packaged in a 5-pin plastic SIP.
FEATURES
For Sensing Motion of Ferrous Targets
Wide Operating Temperature Range
Operation to 30 kHz
Resistant to EMI
Large Effective Air Gap
4.5 V to 24 V Operation
Output Compatible With All Logic Families
Reverse Battery Protection
Resistant to Physical Stress
Operating Temperature Range,
TA ............................... -40°C to +150°C
■
■
■
■
■
■
■
■
■
Storage Temperature Range,
TS ............................... -65°C to +170°C
Always order by complete part number, e.g., A3064LKA .
Reverse Battery Voltage, VRCC .......... -30 V
Magnetic Flux Density, B ............ Unlimited
Output Off Voltage, VOUT ...................... 24 V
Output Current, IOUT ......................... 25 mA
Package Power Dissipation,
PD ............................................ 500 mW
3064
HALL-EFFECT
GEAR-TOOTH SENSOR IC
—AC COUPLED
1
SUPPLY
FUNCTIONAL BLOCK DIAGRAM
REG
OUTPUT
2
+
X
3
X
GROUND
5
4
FILTER
FILTER
Dwg. FH-008-1
ELECTRICAL CHARACTERISTICS over operating temperature and supply voltage range.
Limits
Characteristic
Symbol
Supply Voltage
VCC
Output Saturation Voltage
Test Conditions
Operating
Min.
Typ.
Max.
Units
4.5
—
24
V
VOUT(SAT)
IOUT = 18 mA, B < BRP
—
141
400
mV
Output Leakage Current
I OFF
VOUT = 24 V, B > BOP
—
—
5.0
µA
Supply Current
ICC
B < BRP
—
11
20
mA
B > BOP
—
9.6
—
mA
-3 dB
30
—
—
kHz
High-Frequency Cutoff
fcoh
Output Rise time
tr
VOUT = 12 V, RL = 820 Ω
—
0.04
0.2
µs
Output Fall time
tf
VOUT = 12 V, RL = 820 Ω
—
0.18
0.3
µs
MAGNETIC CHARACTERISTICS over operating temperature and supply voltage range.
Limits
Characteristic
Symbol
Operate Point
BOP
Release Point
Hysteresis
Test Conditions
Min.
Typ.
Max.
Units
Output switches on to off
0
15
27.5
G
BRP
Output switches off to on
-12.5
0
7.5
G
Bhys
BOP - BRP
5.0
15
35
G
NOTES: 1. Magnetic switch points are specified as the difference in magnetic fields at the two Hall elements.
2. As used here, negative flux densities are defined as less than zero (algebraic convention).
3. Typical values are at T A = 25°C and VCC = 12 V.
4. 1 gauss (G) is exactly equal to 0.1 millitesla (mT).
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 2001 Allegro MicroSystems, Inc.
3064
HALL-EFFECT
GEAR-TOOTH SENSOR IC
—AC COUPLED
TYPICAL OPERATING CHARACTERISTICS
SWITCH POINTS
30
DIFFERENTIAL FLUX DENSITY IN GAUSS
V
= 12 V
CC
20
OPERATE POINT
10
0
-10
RELEASE POINT
-50
-25
0
25
75
50
100
125
150
AMBIENT TEMPERATURE IN °C
Dwg. GH-056-1
OUTPUT SATURATION VOLTAGE
200
I OUT = 18 mA
I OUT = 18 mA
V CC = 12 V
TA= +25°C
SATURATION VOLTAGE IN mV
SATURATION VOLTAGE IN mV
300
200
100
0
-50
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN °C
100
50
0
5
10
15
20
25
SUPPLY VOLTAGE IN VOLTS
Dwg. GH-029-6
www.allegromicro.com
150
Dwg. GH-055-2
3
3064
HALL-EFFECT
GEAR-TOOTH SENSOR IC
—AC COUPLED
TYPICAL OPERATING CHARACTERISTICS
SUPPLY CURRENT
20
20
VCC = 24 V
15
SUPPLY CURRENT IN mA
SUPPLY CURRENT IN mA
15
B < B RP
10
B > B OP
5
B < B RP
10
B > B OP
5
TA = +25°C
0
-50
-25
0
25
50
75
100
125
0
150
0
5
10
15
20
25
SUPPLY VOLTAGE IN VOLTS
AMBIENT TEMPERATURE IN °C
Dwg. GH-031-3
Dwg. GH-028-9
APPLICATIONS INFORMATION
The A3064LKA is a versatile high-precision differential
sensing device that can be used in a wide range of applications.
Careful choice of the sensor IC, target material and shape,
magnet material and shape, and assembly techniques enables
large working air gaps and high switch-point accuracy over the
system operating temperature range.
The devices can be used without a back-biasing magnet.
For example, the device can be used to detect a rotating ring
magnet such as those found in brushless dc motors or in speed
sensing applications.
Device Operation. These sensor ICs each contain two
Hall transducers (E1 and E2) that are used to sense a
magnetic field differential across the face of the IC (see Element
Location drawing). Referring to the Typical Transfer Characteristic (Figure 1), the trigger switches the output off (output
high) when BE1 - BE2 > BOP and switches the output on (output
4
+V
V CC
OUTPUT VOLTAGE
Magnet Biasing. To sense moving non-magnetized
ferrous targets, these devices must be back biased by mounting
the unbranded side on a small permanent magnet. Either
magnetic pole (north or south) can be used.
Figure 1
TYPICAL TRANSFER CHARACTERISTIC
B RP
BOP
VOUT(SAT)
0
-B
0
+B
FLUX DENSITY
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Dwg. GH-007-6
3064
HALL-EFFECT
GEAR-TOOTH SENSOR IC
—AC COUPLED
APPLICATIONS INFORMATION (cont’d)
Figure 2
low) when BE1 - BE2 < BRP. The difference between BOP and
BRP is the hysteresis of the device.
LEADING
EDGE
Note that powering up in the absence of a differential
magnetic field (less than the device BOP and higher than the
device BRP) will allow an indeterminate output state. The
correct output state is warranted after the first excursion beyond
BOP or BRP.
AC-Coupled Operation. Steady-state magnet and
system offsets are eliminated using an on-chip differential bandpass filter. The lower frequency cut-off of this patented filter is
set using an external capacitor, the value of which can range
from 0.01 µF to 10 µF. The high-frequency cut-off of this filter
is set at 30 kHz by an internal integrated capacitor.
The differential structure of this filter improves the ability
of the IC to reject single-ended noise on the ground or supply
line and, as a result, makes it more resistant to radio-frequency
and electromagnetic interference typically seen in hostile
remote-sensing environments. This filter configuration also
increases system tolerance to capacitor degradation at high
temperatures, allowing the use of an inexpensive external
ceramic capacitor.
Low-Frequency Operation. Low-frequency operation
of the device is set by the value of an external capacitor.
Ideally, the differential flux density range (determined by the
applied target) vs. air gap assumes a perfect sinusoidal input.
Figure 3 provides the low-frequency cut-off (-3 dB point) of the
filter as a function of capacitance value. This information
should be used with care. In reality, when used with gear teeth,
GEAR
DIRECTION
OF ROTATION
E2
E1
NORTH
SOUTH
4300 G
(a)
B &B
E1
E2
4150 G
150 G
BOP= +15 G
B –B
E1
(b)
0G
E2
B RP= 0 G
-150 G
V
OUT
(c)
V
OUT(SAT)
OUTPUT DUTY CYCLE ≈ 50%
Dwg. WH-003-3
Figure 3
1k
LOW-FREQUENCY CUTOFF IN Hz
Figure 2 relates the output state of a back-biased sensor IC,
with switching characteristics shown in Figure 1, to the target
gear profile and position. Assume a north pole back-bias
configuration (equivalent to a south pole at the face of the
device). The motion of the gear produces a phase-shifted field
at E1 and E2 (Figure 2(a)); internal conditioning circuitry
subtracts the fields at the two elements (Figure 2(b)); this
differential field is band-pass filtered to remove dc offset
components and then fed into a Schmitt trigger; the Schmitt
trigger switches the output transistor at the thresholds BOP and
BRP. As shown (Figure 2(c)), the IC output is low whenever
E2 faces a (ferrous) gear tooth and element E1 faces air.
The output is high when element E1 faces air and E2 faces
a ferrous target.
TRAILING
EDGE
100
10
1.0
0.1
0.01
0.1
1.0
10
CAPACITANCE IN µF
Dwg. GH-025
www.allegromicro.com
5
3064
HALL-EFFECT
GEAR-TOOTH SENSOR IC
—AC COUPLED
APPLICATIONS INFORMATION (cont’d)
the teeth create transitions in the magnetic field that have a
much higher frequency content than the basic rotational speed
of the target. This allows the device to work with speeds much
lower than those indicated by the graph for a given capacitor
value.
Capacitor Characteristics. The major requirement for
the external capacitor is its ability to operate in a bipolar (nonpolarized) mode. Another important requirement is the low
leakage current of the capacitor (equivalent parallel resistance
should be greater than 500 kΩ). To maintain proper operation
with frequency, capacitor values should be held to within ±30%
over the operating temperature range. The commonly available
Z5U ceramic capacitor temperature code should not be used in
this application.
Magnet Selection. The A3064LKA can be used with a
wide variety of commercially available permanent magnets.
The selection of the magnet depends on the operational and
environmental requirements of the sensing system. For systems
that require high accuracy and large working air gaps or an
extended temperature range, the usual magnet material of
choice is rare-earth samarium cobalt (SmCo). This magnet
material has a high energy product and can operate over an
extended temperature range. For systems that require low-cost
solutions for an extended temperature range, AlNiCo 8 can be
used. Due to its relatively low energy product, smaller operational air gaps can be expected. Neodymium iron boron
(NeFeB) can be used over moderate temperature ranges when
large working air gaps are required. Of these three magnet
materials, AlNiCo 8 is the least expensive by volume and SmCo
is the most expensive.
Extensive applications information for Hall-effect devices
is available in:
• Hall-Effect IC Applications Guide, Application Note 27701;
• Hall-Effect Devices: Soldering, Gluing, Potting, Encapsulating, and Lead Forming, Application Note 27703.1;
• Soldering of Through-Hole Hall-Sensor Dervices, Application
Note 27703; and
• Soldering of Surface-Mount Hall-Sensor Devices, Application
Note 27703.2.
All are provided in Allegro Electronic Data Book, AMS-702. or
at
Figure 4
ELEMENT LOCATIONS
(±0.005 [0.13 mm] die placement)
ACTIVE AREA DEPTH
0.0165"
0.42 mm
NOM
0.087"
2.20 mm
0.075"
1.91 mm
E1
E2
A
BRANDED
SURFACE
1
2
3
4
5
Dwg. MH-007E
Allegro
www.allegromicro.com
6
0.083"
2.10 mm
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3064
HALL-EFFECT
GEAR-TOOTH SENSOR IC
—AC COUPLED
CRITERIA FOR DEVICE QUALIFICATION
All Allegro devices are subjected to stringent qualification requirements prior to being released to production.
To become qualified, except for the destructive ESD tests, no failures are permitted.
Qualification Test
Test Method and Test Conditions
Test Length
Samples
Biased Humidity (HAST)
JESD22-A101,
RH = 85%
2000 hrs
320
VCC = VOUT = 12 V
116 pcs at TA = 25°C
116 pcs at TA = 150°C
High-Temperature
Operating Life (HTOL)
JESD22-A108,
TJ ≤ 190°C
2000 hrs
146
VCC = VOUT = 12 V
116 pcs at TA = 25°C
30 pcs at TA = 150°C
Accelerated HTOL
TA = 175°C, TJ ≤ 190°C
500 hrs
50
VCC = VOUT = 7.5 V
Autoclave, Unbiased
JESD22-A102, Condition C,
TA = 121°C at 15 psig
192 hrs
77
Solder Heat
Comments
22
High-Temperature
(Bake) Storage Life
MIL-STD-883, Method 1008,
TA = 170°C
2000 hrs
77
Temperature Cycle
(unbiased)
MIL-STD-883, Method 1010,
+25°C to +150°C
2000 cycles
153
ESD,
Human Body Model
MIL-STD-883, Method 3015
Pre/Post
Reading
3 per
test
Test to failure,
All leads > 2 kV
The products described herein are manufactured under one or
more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283;
5,389,889; 5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719;
5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents
pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to
time, such departures from the detail specifications as may be
required to permit improvements in the performance, reliability, or
manufacturability of its products. Before placing an order, the user is
cautioned to verify that the information being relied upon is current.
Allegro products are not authorized for use as critical components
in life-support appliances, devices, or systems without express written
approval.
The information included herein is believed to be accurate and
reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of
third parties that may result from its use.
www.allegromicro.com
7
3064
HALL-EFFECT
GEAR-TOOTH SENSOR IC
—AC COUPLED
Dimensions in Inches
Dimensions in Millimeters
(controlling dimensions)
(for reference only)
0.252
0.247
6.40
6.27
0.063
0.059
1.60
1.50
0.181
0.176
4.60
4.47
45°
0.083
MAX
1
2
3
4
45°
0.018
5
2.11
MAX
0.0173
0.0138
0.600
0.560
SEE NOTE
1
2
3
4
0.46
5
0.44
0.35
15.24
14.23
SEE NOTE
0.0189
0.0142
0.050
BSC
Dwg. MH-010H in
0.48
0.36
1.27
BSC
Dwg. MH-010H mm
Horizontal-Mount Lead Form (order A3064LKA-TL)
2.41
0.095
±0.13
±0.005
0.051
0.002
MAX
MAX
0.004 0°–8°
MAX
NOTES:
8
0.10
0.020
MIN
FLAT
0°–8°
MAX
Dwg. MH-015 in
0.51
MIN
FLAT
1.
Tolerances on package height and width represent allowable mold offsets.
Dimensions given are measured at the widest point (parting line).
2.
Exact body and lead configuration at vendor s option within limits shown.
3.
Height does not include mold gate flash.
4.
Recommended minimum PWB hole diameter to clear transition area is 0.035 (0.89 mm).
5.
Where no tolerance is specified, dimension is nominal.
6.
Supplied in bulk pack (500 pieces per bag).
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Dwg. MH-015 mm
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