ATS625LSGTN-T [ALLEGRO]
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor; 真零速低抖动高精度齿轮齿传感器
| 型号： | ATS625LSGTN-T |
| 厂家： | 
ALLEGRO MICROSYSTEMS |
| 描述： | True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor |
| 文件： | 总21页 (文件大小：623K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
ATS625LSG
True Zero-Speed Low-Jitter
High Accuracy Gear Tooth Sensor
The ATS625 true zero-speed gear tooth sensor is an optimized Hall IC and magnet
configuration packaged in a molded module that provides a manufacturer-friendly
solution for digital gear tooth sensing applications. The sensor assembly consists
of an over-molded package that holds together a samarium cobalt magnet, a
pole piece concentrator, and a true zero-speed Hall IC that has been optimized
to the magnetic circuit. This small package can be easily assembled and used in
conjunction with gears of various shapes and sizes.
Package SG, 4-pin Through Hole
The sensor incorporates a dual-element Hall IC that switches in response to
differential magnetic signals created by a ferrous target. Digital processing of the
analog signal provides zero-speed performance independent of air gap as well
as dynamic adaptation of device performance to the typical operating conditions
found in automotive applications (reduced vibration sensitivity). High-resolution
peak detecting DACs are used to set the adaptive switching thresholds of the
device. Switchpoint hysteresis reduces the negative effects of any anomalies in the
magnetic signal associated with the targets used in many automotive applications.
This sensor system is optimized for crank applications that utilize targets that
possess signature regions.
TheATS625 is provided in a 4-pin SIP. The Pb (lead) free option, available by
special request, has a 100% matte tin plated leadframe.
Features and Benefits
1
2
3
4
ꢀHighly repeatable over operating temperature range
ꢀTight timing accuracy over operating temperature range
ꢀTrue zero-speed operation
1. VCC
ꢀAir-gap–independent switchpoints
ꢀVibration immunity
ꢀLarge operating air gaps
2. VOUT
3. AUX
4. GND
ꢀDefined power-on state
ꢀWide operating voltage range
ꢀDigital output representing target profile
ꢀSingle-chip sensing IC for high reliability
ꢀSmall mechanical size
ABSOLUTE MAXIMUM RATINGS
Supply Voltage*, V CC .......................................26.5 V
Reverse-Supply Voltage, VRCC ........................–18 V
Reverse-Supply Current, IRCC ........................50 mA
Reverse-Output Voltage, VROUT .....................–0.5 V
Continuous Output Current, IOUT ...................25 mA
Output Sink Current, IOUT ............................. 10 mA
Operating Temperature
Ambient, TA, Range L................–40ºC to 150ºC
Maximum Junction, TJ(max)........................165ºC
Maximum Junction ≤100 hr, TJ(max100)......180ºC
Storage Temperature, TS ..................–65ºC to 170ºC
*See the Power Derating section.
ꢀOptimized Hall IC magnetic system
ꢀFast start-up
ꢀAGC and reference adjust circuit
ꢀUndervoltage lockout
Use the following complete part numbers when ordering:
Part Number
Pb-free
–
Packing1
ATS625LSGTN
Tape and Reel 13-in. 800 pcs./reel
ATS625LSGTN-T
Yes2
1Contact Allegro for additional packing options.
2Available by special request only.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ATS625LSG-DS, Rev. 1
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Functional Block Diagram
V+
VCC
Voltage
Regulator
Threshold
Comparator
Automatic
PPeak
Gain
Control
PDAC
PThresh
NThresh
VPROC
Threshold
Logic
Reference
Generator
Hall
Amp
0.1 F
CBYPASS
NPeak
NDAC
VOUT
Current
Limit
Output
Transistor
GND
AUX
(Recommended)
Allegro MicroSystems, Inc.
2
115 Northeast Cutoff, Box 15036
ATS625LSG-DS, Rev. 1
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Operating Characteristics Valid at TA = –40°C to 150°C, TJ ≤T J(max), over full range of AG, unless otherwise noted; typical
operating parameters: VCC = 12 V and TA = 25°C
Characteristic
ELECTRICAL CHARACTERISTICS
Supply Voltage
Symbol
Test Conditions
Min.
Typ.
Max.
Units
VCC
VCCUV
IRCC
VZ
Operating; TJ < TJmax
4.0
–
–
–
–
–
24
< VCC(min)
–10
V
V
Undervoltage Lockout
Reverse Supply Current
Supply Zener Clamp Voltage1
VCC = –18 V
ICC = 17 mA
–
mA
V
28
–
Supply Zener Current2
IZ
VS = 28 V
–
–
17
mA
Output OFF
Output ON
–
–
8.5
8.5
14
14
mA
mA
Supply Current
ICC
POWER-ON CHARACTERISTICS
Power-On State
SPO
tPO
–
–
High
–
–
V
Power-On Time
Gear Speed < 100 RPM; VCC > VCC min
200
µs
OUTPUT STAGE
Low Output Voltage
Output Current Limit
Output Leakage Current
Output Rise Time
Output Fall Time
VOUT(SAT) ISINK = 20 mA, Output = ON
IOUT(LIM) VOUT = 12 V, TJ < TJmax
IOUT(OFF) Output = OFF, VOUT = 24 V
–
25
–
200
45
–
450
70
10
2
mV
mA
µA
µs
tr
tf
RL = 500 Ω, CL = 10 pF
RL = 500 Ω, CL = 10 pF
–
1.0
0.6
–
2
µs
SWITCHPOINT CHARACTERISTICS
Speed
S
Reference target 60+2
0
–
–
12000
–
rpm
kHz
Bandwidth
BW
Corresponds to switching frequency – 3 dB
20
% of peak-to-peak signal, AG < AGmax
BIN transitioning from LOW to HIGH
;
Operate Point
Release Point
BOP
BRP
–
–
60
40
–
–
%
%
% of peak-to-peak signal, AG < AGmax
BIN transitioning from HIGH to LOW
;
CALIBRATION
Initial Calibration3
Calibration Update
CalPO
Cal
Start-up
–
1
6
edges
–
Running mode operation
continuous
Continued on the next page...
Allegro MicroSystems, Inc.
3
115 Northeast Cutoff, Box 15036
ATS625LSG-DS, Rev. 1
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Operating Characteristics, continued Valid at TA = –40°C to 150°C, TJ ≤T J(max), over full range of AG, unless otherwise noted;
typical operating parameters: VCC = 12 V and TA = 25°C
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
OPERATING CHARACTERISTICS with 60+2 reference target
Measured from sensor branded face to
target tooth
Operational Air Gap
AG
0.5
–
–
–
–
–
–
2.5
mm
deg.
deg.
deg.
deg.
Relative Timing Accuracy, Sequen-
tial Mechanical Rising Edges
Relative Timing Accuracy, Sequen-
tial Mechanical Falling Edges
Relative Timing Accuracy, Signa-
ture Mechanical Rising Edge4
Relative Timing Accuracy, Signa-
ture Mechanical Falling Edge5
Relative to measurement taken at
AG = 1.5 mm
ERRRR
ERRFF
±0.4
±0.4
±0.4
±1.5
Relative to measurement taken at
AG = 1.5 mm
–
Relative to measurement taken at
AG = 1.5 mm
ERRSIGR
ERRSIGF
–
Relative to measurement taken at
AG = 1.5 mm
–
360° Repeatability, 1000 edges; peak-peak
sinusoidal signal with BPEAK ≥ BIN(min) and
6° period
Relative Repeatability, Sequential
Rising and Falling Edges6
TθE
BIN
–
–
–
0.08
–
deg.
G
Operating Signal7
AG(min) < AG < AG(max)
60
1 Test condition is ICC(max) + 3 mA.
2 Upper limit is ICC(max) + 3 mA.
3 Power-on speed ≤ 200 rpm. Refer to the Sensor Description section for information on start-up behavior.
4 Detection accuracy of the update algorithm for the first rising mechanical edge following a signature region can be adversely affected by the magnetic
bias of the signature region. Please consult with Allegro field applications engineering for aid with assessment of specific target geometries.
5 Detection accuracy of the update algorithm for the falling edge of the signature region is highly dependent upon specific target geometry. Please consult
with Allegro field applications engineering for aid with assessment of specific target geometries.
6 The repeatability specification is based on statistical evaluation of a sample population.
7
Peak-to-peak magnetic flux strength required at Hall elements for complying with operational characteristics.
Allegro MicroSystems, Inc.
4
115 Northeast Cutoff, Box 15036
ATS625LSG-DS, Rev. 1
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Reference Target (Gear) Information
REFERENCE TARGET 60+2
Characteristics
Symbol
Test Conditions
Typ.
Units
Symbol Key
Outside Diameter
Do
Outside diameter of target
120
mm
Breadth of tooth, with respect
to sensor
Face Width
F
t
6
3
mm
mm
Branded Face
of Sensor
ØDO
Length of tooth, with respect
to sensor; measured at Do
F
Circular Tooth Length
ht
Length of signature tooth,
with respect to sensor; mea-
sured at Do
Signature Region Cir-
cular Tooth Length
tSIG
15
3
mm
mm
Length of valley, with respect
to sensor; measured at Do
Circular Valley Length
tv
Air Gap
Tooth Whole Depth
Material
ht
3
–
mm
–
Low Carbon Steel
Signature Region
Pin 4
Pin 1
Branded Face
of Sensor
Reference Target
60+2
Figure 1. Configuration with Spur Gear Reference Target
Although these parameters apply to targets of traditional
geometry (radially oriented teeth with radial sensing, shown in
figure 1), they also can be applied in applications using stamped
targets (an aperture or rim gap punched out of the target mate-
rial) and axial sensing. For stamped geometries with axial sens-
ing, the valley depth, ht, is intrinsically infinite, so the criteria for
tooth width, t, valley width, tv, tooth material thickness, F, and
material specification need only be considered for reference. For
example, F can now be < 3 mm.
For the generation of adequate magnetic field levels, the fol-
lowing recommendations should be followed in the design and
specification of targets:
• 2 mm < tooth width, t < 4 mm
• Valley width, tv > 2 mm
• Valley depth, ht > 2 mm
• Tooth thickness, F ≥ 3 mm
• Target material must be low carbon steel
Allegro MicroSystems, Inc.
5
115 Northeast Cutoff, Box 15036
ATS625LSG-DS, Rev. 1
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Characteristic Data: Electrical
I
Versus V
CC
I
Versus T
A
CC(ON)
CC(ON)
14
13
12
11
10
9
14
13
12
11
10
9
Vcc = 26.5V
Vcc = 20V
Vcc = 12V
Vcc = 4V
T
A
(°C)
V
CC
(V)
-40
26.5
20.0
12.0
4.0
0
25
85
8
8
150
7
7
6
6
5
5
-50
-25
0
25
50
75
100
125
150
175
0
5
10
15
20
25
30
Temperature (°C)
Voltage (V)
I
Versus V
I Versus T
CC(OFF) A
CC(OFF)
CC
14
13
12
11
10
9
14
13
12
11
10
9
Vcc = 24V
Vcc = 20V
Vcc = 12V
Vcc = 4V
T
A
(°C)
V
CC
(V)
-40
0
24.0
20.0
12.0
4.0
25
85
8
8
150
7
7
6
6
5
5
-50
-25
0
25
50
75
100
125
150
175
0
5
10
15
20
25
30
Voltage (V)
Temperature (°C)
I
Versus T
V Versus T
OUT(SAT) A
OUT(OFF)
A
400
350
300
250
200
150
100
50
10
8
6
4
I
(mA)
25
20
15
10
5
OUT
V
(V)
OUT
2
26.5
20.0
12.0
4.0
0
-2
-4
-6
-8
-10
0
-50 -25
0
25
50
75 100 125 150 175
-50 -25
0
25
50
75 100 125 150 175
Temperature (°C)
Temperature (°C)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
6
ATS625LSG-DS, Rev. 1
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Characteristic Data: Relative Timing Accuracy
Relative Timing Accuracy Versus Speed
Signature Tooth Rising Edge
0.5 mm Air Gap
Relative Timing Accuracy Versus Ambient
Signature Tooth Rising Edge
0.5 mm Air Gap
1.5
1.5
1.0
1.0
0.5
S (rpm)
T
A
(°C)
50
0.5
–40
0
100
500
0.0
0.0
25
1000
1500
2000
85
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
150
-50
0
50
100
150
200
500
1000
1500
2000
2500
0
Target Speed, S (rpm)
Temperature, TA (°C)
Relative Timing Accuracy Versus Speed
Signature Tooth Falling Edge
0.5 mm Air Gap
Relative Timing Accuracy Versus Ambient
Signature Tooth Falling Edge
0.5 mm Air Gap
1.5
1.5
1.0
1.0
0.5
S (rpm)
50
T
A
(°C)
0.5
–40
0
100
500
0.0
0.0
25
1000
1500
2000
85
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
150
-50
0
50
100
150
200
0
500
1000
1500
2000
2500
Temperature, T (°C)
A
Target Speed, S (rpm)
Relative Timing Accuracy Versus Ambient
Rising Edge Following Signature Tooth
0.5 mm Air Gap
Relative Timing Accuracy Versus Speed
Rising Edge Following Signature Tooth
0.5 mm Air Gap
1.5
1.0
1.5
1.0
0.5
T
A
(°C)
S (rpm)
50
0.5
–40
0
100
0.0
0.0
500
25
1000
1500
2000
85
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
150
0
500
1000
1500
2000
2500
-50
0
50
100
150
200
Target Speed, S (rpm)
Temperature, TA (°C)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
7
ATS625LSG-DS, Rev. 1
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Relative Timing Accuracy Versus Speed
Signature Tooth Rising Edge
2.5 mm Air Gap
Relative Timing Accuracy Versus Ambient
Signature Tooth Rising Edge
2.5 mm Air Gap
1.5
1.5
1.0
1.0
0.5
S (rpm)
T
A
(°C)
50
0.5
–40
0
100
500
0.0
0.0
25
1000
1500
2000
85
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
150
-50
0
50
100
150
200
500
1000
1500
2000
2500
0
Target Speed, S (rpm)
Temperature, TA (°C)
Relative Timing Accuracy Versus Speed
Signature Tooth Falling Edge
2.5 mm Air Gap
Relative Timing Accuracy Versus Ambient
Signature Tooth Falling Edge
2.5 mm Air Gap
1.5
1.5
1.0
1.0
0.5
S (rpm)
50
T
A
(°C)
0.5
–40
0
100
500
0.0
0.0
25
1000
1500
2000
85
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
150
-50
0
50
100
150
200
0
500
1000
1500
2000
2500
Temperature, T (°C)
A
Target Speed, S (rpm)
Relative Timing Accuracy Versus Ambient
Rising Edge Following Signature Tooth
2.5 mm Air Gap
Relative Timing Accuracy Versus Speed
Rising Edge Following Signature Tooth
2.5 mm Air Gap
1.5
1.0
1.5
1.0
0.5
T
A
(°C)
S (rpm)
50
0.5
–40
0
100
0.0
0.0
500
25
1000
1500
2000
85
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
150
0
500
1000
1500
2000
2500
-50
0
50
100
150
200
Target Speed, S (rpm)
Temperature, TA (°C)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
8
ATS625LSG-DS, Rev. 1
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Relative Timing Accuracy Versus Air Gap
Signature Tooth Rising Edge
Relative Timing Accuracy Versus Air Gap
Signature Tooth Falling Edge
T
A
= –40, 0, 25, 85, 150 (°C)
T = –40, 0, 25, 85, 150 (°C)
A
S = 50, 100, 500, 1000, 1500, 2000 (rpm)
S = 50, 100, 500, 1000, 1500, 2000 (rpm)
2.0
1.5
2.0
1.5
1.0
1.0
0.5
0.5
0.0
0.0
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
0.0
0.5
1.0 1.5
Air Gap (mm)
2.0
2.5
3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Air Gap (mm)
Relative Timing Accuracy Versus Air Gap
Rising Edge Following Signature Tooth
T
A
= –40, 0, 25, 85, 150 (°C)
S = 50, 100, 500, 1000, 1500, 2000 (rpm)
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
0
0.5
1.0
1.5
2.0
2.5
3.0
Air Gap (mm)
Characteristic Data: Repeatability
360° Repeatability Versus Air Gap
Sequential Tooth Falling Edge
S = 1000 rpm
0.25
T
A
(°C)
0.20
0.15
0.10
0.05
0
–40
25
150
0
1.0
2.0
3.0
4.0
Air Gap (mm)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
9
ATS625LSG-DS, Rev. 1
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Sensor Description
the magnetic gradient created by the passing of a ferrous object.
Assembly Description
This is illustrated in figures 2 and 3. The differential output of
the two elements is converted to a digital signal that is processed
to provide the digital output.
The ATS625LSG true zero-speed gear tooth sensor is a com-
bined Hall IC-magnet configuration that is fully optimized to
provide digital detection of gear tooth edges. This sensor is
integrally molded into a plastic body that has been optimized for
size, ease of assembly, and manufacturability. High operating
temperature materials are used in all aspects of construction.
Switching Description
After proper power is applied to the component, the sensor is
then capable of providing digital information that is representa-
tive of the profile of a rotating gear, as illustrated in figure 4.
No additional optimization is needed and minimal processing
circuitry is required. This ease of use reduces design time and
incremental assembly costs for most applications.
Sensing Technology
The gear tooth sensor contains a single-chip differential Hall
effect sensor IC, a 4-pin leadframe, a samarium cobalt magnet,
and a flat ferrous pole piece. The Hall IC consists of two Hall
elements spaced 2.2 mm apart, and each independently measures
Target (Gear)
Element Pitch
Branded Face
Rotating Target
of Sensor
Hall Element 2
Hall Element 1
Hall IC
Pole Piece
(Concentrator)
South Pole
North Pole
Dual-Element
Hall Effect Device
1
4
Back-biasing Magnet
Plastic
(Pin n >1 Side)
(Pin 1 Side)
Figure 3. This left-to-right (pin 1 to pin 4) direction of target rotation
results in a high output signal when a tooth of the target gear is centered
over the face of the sensor. A right-to-left (pin 4 to pin 1) rotation inverts
the output signal polarity.
Figure 2. Device Cross Section. Relative motion of the target is detected
by the dual Hall elements mounted on the Hall IC. This view is from the
side opposite the pins.
Target
Mechanical Profile
Signature Tooth
B+
Target
Magnetic Profile
BIN
Sensor Output
Switch State
On Off On Off On Off On Off On
Off
On Off On Off On Off
V+
Sensor Output
Electrical Profile
Target Motion from
Pin 1 to Pin 4
VOUT
V+
Sensor Output
Electrical Profile
Target Motion from
Pin 4 to Pin 1
VOUT
Figure 4. The magnetic profile reflects the geometry of the target, allowing the device to present an accurate digital output response.
Allegro MicroSystems, Inc.
10
115 Northeast Cutoff, Box 15036
ATS625LSG-DS, Rev. 1
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
figure 5 is the basic configuration required for proper device
Undervoltage Lockout
operation. Contact Allegro field applications engineering for
information on the circuitry required for compliance to various
EMC specifications.
When the supply voltage falls below the undervoltage lockout
level, VCCUV, the device switches to the OFF state. The device
remains in that state until the voltage level is restored to to the
VCC operating range. Changes in the target magnetic profile
have no effect until voltage is restored. This prevents false sig-
nals caused by undervoltage conditions from propagating to the
output of the sensor.
Internal Electronics
The ATS625LSG contains a self-calibrating Hall effect IC
that possesses two Hall elements, a temperature compensated
amplifier and offset cancellation circuitry. The IC also contains
a voltage regulator that provides supply noise rejection over the
operating voltage range. The Hall transducers and the electron-
ics are integrated on the same silicon substrate by a proprietary
BiCMOS process. Changes in temperature do not greatly affect
this device due to the stable amplifier design and the offset rejec-
tion circuitry.
Power Supply Protection
The device contains an on-chip regulator and can operate over
a wide range of supply voltage levels. For applications using an
unregulated power supply, transient protection must be added
externally. For applications using a regulated supply line, EMI
and RFI protection may still be required. The circuit shown in
VS
1
VCC
RPU
CBYPASS
0.1 µF
3
ATS625
Sensor Output
2
AUX
VOUT
GND
4
Figure 5. Power Supply Protection Typical Circuit
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
11
ATS625LSG-DS, Rev. 1
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Sensor Operation Description
Power-On State
At power-on, the device is guaranteed to initialize in the OFF
state, with VOUT high.
the, target feature (tooth, rising edge, falling edge, or valley) that
is centered on the device at power-on, and fact that the sensor
powers-on in the OFF state,with VOUT high, regardless of the
eventual direction of target rotation. The interaction of these fac-
tors results in a number of possible power-on scenarios. These
are diagrammed in figure 6. In all start-up scenarios, the correct
number of output edges is provided, but the accuracy of the first
two edges may be compromised.
First Edge Detection
The device uses the first two mechanical edges to synchronize
with the target features (tooth or valley) and direction of rotation
of the target. The device is synchonized by the third edge. The
actual behavior is affected by: target rotation direction relative to
Sensor
Pin 1 Side
Sensor
Pin 4 Side
Target Motion Relative to Sensor
Target Mechanical Profile
Target Magnetic Profile
Sensor Output, VOUT
(Start-up over valley)
(Start-up over rising edge)
(A) Target relative movement
as shown in figure 3. Output
signal is high over the tooth.
(Start-up over tooth)
(Start-up over falling edge)
Sensor start-up location
Sensor
Pin 4 Side
Sensor
Pin 1 Side
Target Motion Relative to Sensor
Target Mechanical Profile
Target Magnetic Profile
Sensor Output, VOUT
(Start-up over valley)
(B) Target relative movement
opposite that shown in figure 3.
Output signal is low over the tooth.
(Start-up over rising edge)
(Start-up over tooth)
(Start-up over falling edge)
Sensor start-up location
Figure 6. Start-up Position And Relative Motion Effects on First Device Output Switching. Panel A shows the effects when the
target is moving from pin 1 toward pin 4 of the device; VOUT goes high at the approach of a tooth. When the target is moving
in the opposite direction, as in panel B, the polarity of the device output inverts; VOUT goes low at the approach of a tooth.
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ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
adjusted, keeping the internal signal amplitude constant over the
AGC (Automatic Gain Control)
air gap range of the device, AG. This feature ensures that opera-
tional characteristics are isolated from the effects of changes in
AG. The effect of AGC is shown in figure 7.
The AGC feature is implemented by a unique patented self-
calibrating circuitry. After each power-on, the device measures
the peak-to-peak magnetic signal. The gain of the sensor is then
Differential Electrical Signal versus Target Rotation
at Various Air Gaps, Without AGC
Differential Electrical Signal versus Target Rotation
at Various Air Gaps, With AGC
1000
1000
AG:
0.25 mm
800
800
0.50 mm
1.00 mm
AG:
0.25 mm
600
600
1.50 mm
0.50 mm
1.00 mm
2.00 mm
400
400
1.50 mm
2.00 mm
200
200
0
0
-200
-400
-600
-800
-1000
-200
-400
-600
-800
-1000
0
3
6
9
12
15
18
21
24
0
3
6
9
12
15
18
21
24
Target Rotation (°)
Target Rotation (°)
Figure 7. Effect of AGC. The left panel shows the process signal, VPROC, without AGC. The right panel shows the effect with
AGC. The result is a normalized VPROC, which allows optimal performance by the rest of the circuits that reference this signal.
processed signal, VPROC, and use it as a reference for the Thresh-
old Comparator subcircuit, which controls device switching. If
induced offsets bias the absolute signal up or down, AGC and
the dynamic DAC behavior work to normalize and reduce the
impact of the offset on sensor performance.
Offset Adjustment
In addition to normalizing performance over varying AG, the
gain control circuitry also reduces the effect of chip, magnet,
and installation offsets. This is accomplished using two DACs
(D to A converters) that capture the peaks and valleys of the
Allegro MicroSystems, Inc.
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ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
ing from the previous two edges. Because variations are tracked
SWITCHPOINTS
in real time, the sensor has high immunity to target run-out and
retains excellent accuracy and functionality in the presence of
both run-out and transient mechanical events. Figure 9 shows
how the sensor uses historical data to provide the switching
threshold for a given edge.
Switchpoints in the ATS625 are a percentage of the amplitude of
the signal, VPROC, after normalization with AGC. In operation,
the actual switching levels are determined dynamically. Two
DACs track the peaks of VPROC (see the Update subsection).
The switching thresholds are established at 40% and 60% of the
values held in the two DACs. The proximity of the thresholds
near the 50% level ensures the most accurate and consistent
switching, because it is where the slope of VPROC is steepest and
least affected by air gap variation.
Dynamic BOP Threshold Determination
The low hysteresis, 20%, provides high performance over vari-
ous air gaps and immunity to false switching on noise, vibration,
backlash, or other transient events.
V+
100
Figure 8 graphically demonstrates the establishment of the
switching threshold levels.Because the thresholds are established
dynamically as a percentage of the peak-to-peak signal, the
effect of a baseline shift is minimized. As a result, the effects of
offsets induced by tilted or off-center installation are minimized.
60
B
OP
0
UPDATE
The ATS625 incorporates an algorithm that continuously moni-
tors the system and updates the switching thresholds accordingly.
The switchpoint for each edge is determined by the signal result-
On
Off
(A)
Switching Threshold Levels
Level
Dynamic BRP Threshold Determination
At Constant V
PROC
V+
V+
100
100
60
40
B
B
OP
B
RP
40
0
RP
0
Off
On
Off
On
Off
On
(B)
Figure 8. Switchpoint Relationship to Thresholds.The device switches
when VPROC passes a threshold level, BOP or BRP, while changing in the
corresponding direction: increasing for a BOP switchpoint, and decreasing
for a BRP switchpoint.
Figure 9. Switchpoint Determination. The two previous VPROC peaks are
used to determine the next threshold level: panel A, operate point, and
panel B, release point.
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ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Sensor and Target Evaluation
Magnetic Profile
A single curve can be derived from this map data, and be used to
describe the peak-to-peak magnetic field strength versus the size
of the air gap, AG. This allows determination of the minimum
amount of magnetic flux density that guarantees operation of the
sensor, BIN, so the system designer can determine the maximum
allowable AG for the sensor and target system. Referring to fig-
ure 11, a BIN of 60 G corresponds to a maximum AG of approxi-
mately 2.5 mm.
In order to establish the proper operating specification for a
particular sensor and target system, a systematic evaluation of
the magnetic circuit should be performed. The first step is the
generation of a magnetic map of the target. By using a calibrated
device, a magnetic profile of the system is made. Figure 10 is a
magnetic map of the 60+2 reference target.
Magnetic Map, Reference Target 60+2 with ATS625
300
250
200
150
100
50
AG
(mm)
0.75
1.00
1.50
2.00
2.50
3.00
0
-50
-100
-150
-200
-250
-300
-350
-400
0
30
60
90
120
150
180
Target Rotation (°)
Air Gap Versus Magnetic Field, Reference Target 60+2 with ATS625
800
700
600
500
400
300
200
100
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
AG (mm)
Figure 10. Magnetic Data for the Reference Target 60+2 with ATS625. In the top panel, the Signature Region appears in the center of the plot.
Allegro MicroSystems, Inc.
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ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
scope, close to the desired output edge, the speed variations that
ACCURACY
occur within a single revolution of the target are effectively nul-
lified. Because the trigger event occurs a very short time before
the measured event, little opportunity is given for measurement
system jitter to impact the time-based measurements.
While the update algorithm will allow the sensor to adapt to
typical air gap variations, major changes in air gap can adversely
affect switching performance. When characterizing sensor
performance over a significant air gap range, be sure to re-power
the device at each test at different air gaps. This ensures that
self-calibration occurs for each installation condition. See the
Operating Characteristics table and the charts in the Character-
istic Data: Relative Timing Accuracy section for performance
information.
After the data is taken on the oscilloscope, statistical analysis
of the distribution is made to quantify variability and capabil-
ity. Although complete repeatability results can be found in the
Characteristic Data: Repeatability section, figure 11 shows the
correlation between magnetic signal strength and repeatability.
Because an direct relationship exists between magnetic signal
strength and repeatability, optimum repeatability performance
can be attained through minimizing the operating air gap and
optimizing the target design.
REPEATABILITY
Repeatability measurement methodology has been formulated to
minimize the effect of test system jitter on device measurements.
By triggering the measurement instrument, such as an oscillo-
Target Mechanical Profile
Low Resolution Encoder
Oscilloscope triggers at
n events after low-resolution pulse
Next high-resolution encoder pulse
(at target edge)
High Resolution Encoder
Sensor Output
Electrical Profile
(target movement
from pin 1 to pin 4)
Oscilloscope trace
of 1000 sweeps for
the same output edge
Statistical distribution
of 1000 sweeps
X
Figure 11. Repeatability Measurement Methodology
Allegro MicroSystems, Inc.
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ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Power Derating
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
Test Conditions*
Value Units
Minimum-K PCB (single layer, single-sided, with copper limited to
solder pads)
126
84
ºC/W
ºC/W
RθJA
Package Thermal Resistance
Low-K PCB (single-layer, single-sided with copper limited to
solder pads and 3.57 in.2 (23.03 cm2) of copper area each side)
*Additional information is available on the Allegro Web site.
Power Derating Curve
TJ(max) = 165ºC
30
25
20
15
10
5
V
CC(max)
Low-K PCB
(RθJA = 84 ºC/W)
Minimum-K PCB
(RθJA = 126 ºC/W)
V
CC(min)
0
20
40
60
80
100
120
140
160
180
Power Dissipation Versus Ambient
for Sample PCBs
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
20
40
60
80
100
120
140
160
180
Temperature, T (°C)
A
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ATS625LSG-DS, Rev. 1
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
The device must be operated below the maximum junction
Example: Reliability for VCC at TA=150°C, package SG, using
temperature of the device, TJ(max). Under certain combinations of
peak conditions, reliable operation may require derating sup-
plied power or improving the heat dissipation properties of the
application. This section presents a procedure for correlating
factors affecting operating TJ. (Thermal data is also available on
the Allegro MicroSystems Web site.)
minimum-K PCB.
Observe the worst-case ratings for the device, specifically:
R
θJA=126°C/W, TJ(max) =165°C, VCC(max)=26.5V, and
ICC(max) = 8 mA. Note that ICC(max) at TA=150°C is lower than
the ICC(max) at TA=25°C given in the Operating Characteristics
table.
The Package Thermal Resistance, RθJA, is a figure of merit sum-
marizing the ability of the application and the device to dissipate
heat from the junction (die), through all paths to the ambient air.
Its primary component is the Effective Thermal Conductivity,
K, of the printed circuit board, including adjacent devices and
traces. Radiation from the die through the device case, RθJC, is
relatively small component of RθJA. Ambient air temperature,
TA, and air motion are significant external factors, damped by
overmolding.
Calculate the maximum allowable power level, PD(max). First,
invert equation 3:
∆Tmax = TJ(max) – TA = 165°C–150°C = 15°C
This provides the allowable increase to TJ resulting from internal
power dissipation. Then, invert equation 2:
P
D(max) = ∆Tmax ÷RθJA =15°C÷126 °C/W=119mW
Finally, invert equation 1 with respect to voltage:
The effect of varying power levels (Power Dissipation, PD), can
be estimated. The following formulas represent the fundamental
relationships used to estimate TJ, at PD.
VCC(est) = PD(max) ÷ ICC(max) = 119mW÷8mA=14.9 V
The result indicates that, at TA, the application and device can
dissipate adequate amounts of heat at voltages ≤VCC(est)
.
PD = VIN
I
(1)
(2)
(3)
×
IN
Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reli-
able operation between VCC(est) and VCC(max) requires enhanced
∆T = PD
R
θJA
×
R
θJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and
TJ = TA + ∆T
VCC(max) is reliable under these conditions.
For example, given common conditions such as: TA= 25°C,
IN = 12 V, IIN = 4 mA, and RθJA = 140 °C/W, then:
V
PD = VIN
I
= 12 V 4 mA = 48 mW
×
×
IN
∆T = PD
R
= 48 mW 140 °C/W = 7°C
×
×
θJA
TJ = TA + ∆T = 25°C + 7°C = 32°C
A worst-case estimate, PD(max), represents the maximum allow-
able power level, without exceeding TJ(max), at a selected RθJA
and TA.
Allegro MicroSystems, Inc.
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115 Northeast Cutoff, Box 15036
ATS625LSG-DS, Rev. 1
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Sensor Evaluation: EMC
Characterization Only
Test Name*
ESD – Human Body Model
ESD – Machine Model
Conducted Transients
Direct RF Injection
Reference Specification
AEC-Q100-002
AEC-Q100-003
ISO 7637-1
ISO 11452-7
Bulk Current Injection
TEM Cell
ISO 11452-4
ISO 11452-3
*Please contact Allegro MicroSystems for EMC performance
Mechanical Information
Component
Material
Description
Value
Element Spacing
Hall sensing element spacing
2.2 mm
Back-biasing Magnet
Sensor Package Material
Leads
Rare Earth
Thermoset Epoxy
Copper
South pole behind IC
Maximum Temperature
170°Ca
Solder, Tin/Lead 90/10b
aTemperature excursions of up to 260°C for 2 minutes or less are permitted (based on delamination studies).
bIndustry accepted soldering techniques are acceptable for this package as long as the indicated maximum temperature is not exceeded.
Allegro MicroSystems, Inc.
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ATS625LSG-DS, Rev. 1
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
Package SG, 4-Pin SIP
5.5 .217
E
1.10 .0433
1.10 .0433
C
B
8.0 .315
5.8 .228
2.9 .114
E
0.38 .015
A
4.7 .185
1.7 .067
1
2
3
4
1.08 .043
20.95 .825
0.4 .016
15.3 .602
A
D
.024
0.6
1.27 .050
Dimensions in millimeters. Untoleranced dimensions are nominal.
U.S. Customary dimensions (in.) in brackets, for reference only
Dambar removal protrusion
A
Metallic protrusion, electrically connected to pin 4 and substrate (both sides)
Active Area Depth, 0.43 [.017]
B
C
D
E
Thermoplastic Molded Lead Bar for alignment during shipment
Hall elements, controlling dimension inches
Allegro MicroSystems, Inc.
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www.allegromicro.com
20
ATS625LSG-DS, Rev. 1
ATS625LSG
True Zero-Speed Low-Jitter High Accuracy Gear Tooth Sensor
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 manufactur-
ability 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 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 infringement of patents or other rights of third parties
which may result from its use.
Copyright © 2005, Allegro MicroSystems, Inc.
Allegro MicroSystems, Inc.
21
115 Northeast Cutoff, Box 15036
ATS625LSG-DS, Rev. 1
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
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