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ATS642LSH
ATS642LSH-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
AB SO LUTE MAX I MUM RAT INGS
Supply Voltage, V
CC
..........................................28 V
Reverse-Supply Voltage, V
RCC
........................18 V
Operating Temperature
Ambient,
T
A
,............................... 40C to 150C
Maximum
Junction,
T
J(max)
........................165C
Storage Temperature, T
S
.................. 65C to 170C
Running mode calibration for continu-
ous optimization
Single chip IC for high reliability
Internal current regulator for 2-wire
operation
Small mechanical size (8 mm
diameter x 5.5 mm depth)
Precise duty cycle signal over
operating temperature range
Large operating air gaps
Automatic Gain Control (AGC)
for air
gap independent switchpoints
Automatic Offset Adjustment (AOA)
for signal processing optimization
True zero-speed operation
Undervoltage lockout
Wide operating voltage range
The ATS642LSH is an optimized Hall effect sensing integrated circuit and magnet
combination that provides a user-friendly solution for true zero-speed digital
gear-tooth sensing in two-wire applications. The sensor consists of a single-shot
molded plastic package that includes a samarium cobalt magnet, a pole piece,
and a Hall effect IC that has been optimized to the magnetic circuit. This small
package, with optimized two-wire leadframe, can be easily assembled and used in
conjunction with a wide variety of gear shapes and sizes.
The integrated circuit incorporates a dual element Hall effect sensor and signal
processing that switches in response to differential magnetic signals created
by ferrous gear teeth. The circuitry contains a sophisticated digital circuit to
reduce magnet and system offsets, to calibrate the gain for air gap independent
switchpoints, and to achieve true zero-speed operation. Signal optimization occurs
at power-up through the combination of offset and gain adjust and is maintained
throughout the operating time with the use of a running mode calibration. The run-
ning mode calibration allows immunity to environmental effects such as microos-
cillations of the target or sudden air gap changes.
The regulated current output is configured for two wire applications and the
sensor is ideally suited for obtaining speed and duty cycle information in ABS
(antilock braking systems). The 1.5 mm Hall element spacing is optimized for fine
pitch gear-tooth-based configurations. The package is lead (Pb) free, with 100%
matte tin leadframe plating.
Two-Wire True Zero Speed Miniature Differential
Peak-Detecting Gear Tooth Sensor with Continuous Calibration
Package SH, 4-pin Module
Features and Benefi ts
1. VCC
2. No connection
3. Test pin (fl oat or tie to GND)
4. GND
1 2
3 4
Use the following complete part numbers when ordering:
Part Number
I
CC
Typical
Packing*
ATS642LSHTN-I1-T
6.0 Low to 14.0 High mA
Tape and reel,
13-inch reel
800 pieces/reel
ATS642LSHTN-I2-T
7.0 Low to 14.0 High mA
*Contact Allegro for additional packing options.
2
ATS642LSH-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
True Zero Speed Miniature Differential Peak-Detecting Gear Tooth Sensor
ATS642LSH
Functional Block Diagram
VCC
Automatic Offset
Control
AOA DAC
Hall
Amplifier
AGC DAC
Gain
Tracking
DAC
Peak Hold
Gain Control
Internal Regulator
Test Signals
GND
Test
3
ATS642LSH-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
True Zero Speed Miniature Differential Peak-Detecting Gear Tooth Sensor
ATS642LSH
OPERATING CHARACTERISTICS
using reference target 60-0, T
A
and V
CC
within specifi cation, unless otherwise noted
CHARACTERISTIC
Symbol
Test Conditions
Min.
Typ.
1
Max.
Units
ELECTRICAL CHARACTERISTICS
Supply Voltage
2
V
CC
Operating; T
J
< 165 C
4.0
24
V
Undervoltage Lockout
V
CC(UV)
V
CC
0 5 V and 5 0 V
4.0
V
Supply Zener Clamp Voltage
V
Z
I
CC
= I
CC(max)
+ 3 mA; T
A
= 25C
28
V
Supply Zener Current
I
Z
Test conditions only; V
Z
= 28 V
I
CC(max)
+
3 mA
mA
Supply Current
I
CC(Low)
ATS642LSH-I1 4.0
6.0
8.0
mA
ATS642LSH-I2
5.9
7.0
8.4
mA
I
CC(High)
ATS642LSH-I1 12.0
14.0
16.0
mA
ATS642LSH-I2
11.8
14.0
16.8
mA
Supply Current Ratio
I
CC(High)
/
I
CC(Low)
Ratio of high current to low current
1.85
3.05
Reverse Battery Current
I
RCC
V
RCC
= 18 V
5
mA
POWER-ON STATE CHARACTERISTICS
Power-On State
3
POS
t > t
PO
I
CC(High)
Power-On Time
4
t
PO
Target gear speed < 100 rpm
1
2
ms
OUTPUT STAGE
Output Slew Rate
5
dI/dt
R
LOAD
= 100 , C
LOAD
= 10 pF
10
mA/s
Continued on the next page.
4
ATS642LSH-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
True Zero Speed Miniature Differential Peak-Detecting Gear Tooth Sensor
ATS642LSH
OPERATING CHARACTERISTICS
(continued) using reference target 60-0, T
A
and V
CC
within specifi cation, unless otherwise noted
Characteristic
Symbol
Test Conditions
Min.
Typ.
1
Max.
Units
SWITCHPOINT CHARACTERISTICS
Rotation Speed
S
ROT
Reference Target 60-0
0
8,000
rpm
Analog Signal Bandwidth
BW
Equivalent to f 3 dB
20
40
kHz
Operate Point
B
OP
Transitioning from I
CC(High)
to I
CC(Low)
; positive peak
referenced; AG < AG
MAX
120
mV
Release Point
B
RP
Transitioning from I
CC(Low)
to I
CC(High)
; negative peak
referenced; AG < AG
MAX
120
mV
CALIBRATION
Initial Calibration
C
I
Quantity of rising output (current) edges required for
accurate edge detection
3
Edge
DAC CHARACTERISTICS
Allowable User-Induced Differential
Offset
Output switching only; may not meet datasheet speci-
fi cations
60
G
FUNCTIONAL CHARACTERISTICS
6
Operational Air Gap Range
7
AG
DC within specifi cation
0.5
2.75
mm
Maximum Operational Air Gap
Range
AG
OP(max)
Output switching (no missed edges); DC not
guaranteed
3
mm
Duty Cycle Variation
DC
Wobble < 0.5 mm; Typical value at AG = 1.5 mm, for
max., min., AG within specifi cation
41
61
%
Duty Cycle Pitch Variance
8
E
DC
AG = 1.5 mm
1.5
%
Operating Signal Range
9
Sig
Operating within specifi cation
30
1000
G
Minimum Operating Signal
Sig
OP(min)
Output switching (no missed edges); DC not
guaranteed
20
G
1
Typical values are at T
A
= 25C and V
CC
= 12 V. Performance may vary for individual units, within the specifi ed maximum and minimum limits.
2
Maximum voltage must be adjusted for power dissipation and junction temperature; see
Power Derating
section.
3
Please refer to Sensor Operation section, page 13.
4
Power-On Time includes the time required to complete the internal automatic offset adjust. The DACs are then ready for peak acquisition.
5
dI is the difference between 10% of I
CC(Low)
and 90% of I
CC(High)
, and dt is time period between those two points.
Note: di/dt is dependent upon the value of the bypass capacitor, if one is used.
6
Functional characteristics valid only if magnetic offset is within the specifi ed range for Allowable User Induced Differential Offset.
7
AG is dependent on the available magnetic fi eld. The available fi eld is dependent on target geometry and material, and should be independently
characterized. The fi eld available from the reference target is given in the reference target parameter section of the datasheet.
8
E
DC
represents the difference between consecutive duty cycles, DC(
n)
- DC(
n
-1); Mean 3-sigma.
9
In order to remain in specifi cation, the magnetic gradient must induce an operating signal greater than the minimum value specifi ed. This includes the
effect of target wobble.
5
ATS642LSH-DS
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
True Zero Speed Miniature Differential Peak-Detecting Gear Tooth Sensor
ATS642LSH
REFERENCE TARGET, 60-0 (60 Tooth Target)
Characteristics
Symbol
Test Conditions
Typ.
Units
Symbol Key
Outside Diameter
D
o
Outside diameter of target
120
mm
D
o
h
t
F
Air Gap
Branded Face of Sensor
t
t
v
Face Width
F
Breadth of tooth, with
respect to sensor
6
mm
Angular Tooth Thickness
t
Length of tooth, with
respect to sensor
3
deg
Angular Valley Thickness
t
v
Length of valley, with
respect to sensor
3
deg
Tooth Whole Depth
h
t
3
mm
Material
Low Carbon Steel
Reference Gear Magnetic Gradient Amplitude
With Reference to Air Gap
Air Gap (mm)
Peak-to-Peak Differential B (G)
0
100
200
300
400
500
600
700
800
1
1.5
2
0.5
2.5
3
Reference Gear Magnetic Profile
Two Tooth-to-Valley Transitions
-500
-400
-300
-200
-100
0
100
200
300
400
500
Gear Rotation ()
Differential B* (G)
0
2
4
6
8
10
12
0.50
(mm)
Air Gap
0.50 mm AG
3.00 mm AG
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
Reference Target
60-0
of Sensor
Branded Face
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